\( \newcommand{\coloneqq}{\mathrel{\vcenter{:}}=} \newcommand{\qty}[1]{\left( {#1} \right)} \newcommand{\AA}{{\mathbf{A}}} \newcommand{\CC}{{\mathbf{C}}} \newcommand{\DD}{\mathbb{D}} \newcommand{\EE}{{\mathbb{E}}} \newcommand{\FF}{{ \mathbf{F} }} \newcommand{\GG}{{\mathbf{G}}} \newcommand{\HH}{{\mathbb{H}}} \newcommand{\KK}{{\mathbb{K}}} \newcommand{\LL}{{\mathbb{L}}} \newcommand{\NN}{{\mathbb{N}}} \newcommand{\PP}{{\mathbf{P}}} \newcommand{\QQ}{{\mathbf{Q}}} \newcommand{\RR}{{\mathbf{R}}} \newcommand{\SS}{{\mathbb{S}}} \newcommand{\TT}{{\mathbb{T}}} \newcommand{\UU}{\mathbb{U}} \newcommand{\VV}{{\mathbf{V}}} \newcommand{\ZZ}{{\mathbf{Z}}} \newcommand{\GGr}{{\mathbb{Gr}}} \newcommand{\OP}{{\mathbb{OP}}} \newcommand{\SpSp}{{\mathbb{S}}} \newcommand{\CCpadic}{{ \CC_p }} \newcommand{\CCstar}{\unitsof{\CC}} \newcommand{\FFbar}{{\bar\FF}} \newcommand{\FFp}{{\FF_p}} \newcommand{\FFpn}{{\FF_{p^n}}} \newcommand{\Fpbar}{\bar{\FF_p}} \newcommand{\fq}{{\FF_{q}}} \newcommand{\fqbar}{\bar{\FF_{q}}} \newcommand{\fqr}{{\FF_{q^r}}} \newcommand{\kG}{{kG}} \newcommand{\kk}{{\mathbf{k}}} \newcommand{\QQbar}{{ \bar{ \mathbf{Q} } }} \newcommand{\QQladic}{{ \QQ_\ell }} \newcommand{\QQpadic}{{ \QQ_{\hat p} }} \newcommand{\ZZbar}{{ \bar{ \ZZ } }} \newcommand{\ZZelladic}{{ \ZZ_\ell }} \newcommand{\ZZG}{{\ZZ G}} \newcommand{\ZZH}{{\ZZ H}} \newcommand{\ZZhat}{{ \widehat{ \ZZ } }} \newcommand{\ZZladic}{{ \ZZ_{\hat \ell} }} \newcommand{\ZZpadic}{{ \ZZ_{\hat p} }} \newcommand{\ZZpcomplete}{{ \ZZpadic }} \newcommand{\ZZplocal}{{ L_p \ZZ }} \newcommand{\ZZprof}{{ \hat{\ZZ} }} \newcommand{\ZpZ}{\ZZ/p} \newcommand{\zlnz}{\ZZ/\ell^n\ZZ} \newcommand{\zlz}{\ZZ/\ell\ZZ} \newcommand{\znz}{\ZZ/n\ZZ} \newcommand{\zpz}{\ZZ/p\ZZ} \newcommand{\Banach}{\mathcal{B}} \newcommand{\Hsh}{{ \mathcal{H} }} \newcommand{\mca}{{\mathcal{A}}} \newcommand{\mcb}{{\mathcal{B}}} \newcommand{\mcc}{{\mathcal{C}}} \newcommand{\mcd}{{\mathcal{D}}} \newcommand{\mce}{{\mathcal{E}}} \newcommand{\mcf}{{\mathcal{F}}} \newcommand{\mcg}{{\mathcal{G}}} \newcommand{\mch}{{\mathcal{H}}} \newcommand{\mci}{{\mathcal{I}}} \newcommand{\mcj}{{\mathcal{J}}} \newcommand{\mck}{{\mathcal{K}}} \newcommand{\mcl}{{\mathcal{L}}} \newcommand{\mcm}{{\mathcal{M}}} \newcommand{\mcn}{{\mathcal{N}}} \newcommand{\mco}{{\mathcal{O}}} \newcommand{\mcp}{{\mathcal{P}}} \newcommand{\mcq}{{\mathcal{Q}}} \newcommand{\mcr}{{\mathcal{R}}} \newcommand{\mcs}{{\mathcal{S}}} \newcommand{\mct}{{\mathcal{T}}} \newcommand{\mcTop}{\mathcal{T}\mathsf{op}} \newcommand{\mcu}{{\mathcal{U}}} \newcommand{\mcv}{{\mathcal{V}}} \newcommand{\mcw}{{\mathcal{W}}} \newcommand{\mcx}{{\mathcal{X}}} \newcommand{\mcy}{{\mathcal{Y}}} \newcommand{\mcz}{{\mathcal{Z}}} \newcommand{\OO}{{\mathcal{O}}} \newcommand{\Path}{\mathcal{P}} \newcommand{\liea}{{\mathfrak{a}}} \newcommand{\lieb}{{\mathfrak{b}}} \newcommand{\lied}{{\mathfrak{d}}} \newcommand{\lief}{{\mathfrak{f}}} \newcommand{\lieg}{{\mathfrak{g}}} \newcommand{\liegl}{{\mathfrak{gl}}} \newcommand{\lieh}{{\mathfrak{h}}} \newcommand{\liel}{{\mathfrak{l}}} \newcommand{\lien}{{\mathfrak{n}}} \newcommand{\lieo}{{\mathfrak{o}}} \newcommand{\liep}{{\mathfrak{p}}} \newcommand{\lieq}{{\mathfrak{q}}} \newcommand{\lier}{{\mathfrak{r}}} \newcommand{\lies}{{\mathfrak{s}}} \newcommand{\liesl}{{\mathfrak{sl}}} \newcommand{\lieso}{{\mathfrak{so}}} \newcommand{\liesp}{{\mathfrak{sp}}} \newcommand{\liesu}{{\mathfrak{su}}} \newcommand{\liet}{{\mathfrak{t}}} \newcommand{\lieu}{{\mathfrak{u}}} \newcommand{\lieW}{{\mathfrak{W}}} \newcommand{\liey}{{\mathfrak{y}}} \newcommand{\mfa}{{\mathfrak{a}}} \newcommand{\mfb}{{\mathfrak{b}}} \newcommand{\mfc}{{\mathfrak{c}}} \newcommand{\mfC}{{\mathfrak{C}}} \newcommand{\mfe}{{\mathfrak{e}}} \newcommand{\mff}{{\mathfrak{f}}} \newcommand{\mfF}{{\mathfrak{F}}} \newcommand{\mfg}{{\mathfrak{g}}} \newcommand{\mfh}{{\mathfrak{h}}} \newcommand{\mfk}{{\mathfrak{k}}} \newcommand{\mfm}{{\mathfrak{m}}} \newcommand{\mfn}{{\mathfrak{n}}} \newcommand{\mfo}{{\mathfrak{o}}} \newcommand{\mfp}{{\mathfrak{p}}} \newcommand{\mfq}{{\mathfrak{q}}} \newcommand{\mfr}{{\mathfrak{r}}} \newcommand{\mfs}{{\mathfrak{s}}} \newcommand{\mfS}{{\mathfrak{S}}} \newcommand{\mfu}{{\mathfrak{u}}} \newcommand{\mfv}{{\mathfrak{v}}} \newcommand{\mfX}{{\mathfrak{X}}} \newcommand{\mm}{{\mathfrak{m}}} \newcommand{\bigo}{{ \mathsf{O}}} \newcommand{\Gal}{{ \mathsf{Gal}}} \newcommand{\Herm}{{\mathsf{Herm}}} \newcommand{\AMGM}{{\mathrm{AMGM}}} \newcommand{\CM}{{\mathrm{CM}}} \newcommand{\CR}{{\mathrm{CR}}} \newcommand{\CS}{\mathrm{CS}} \newcommand{\CY}{{ \text{CY} }} \newcommand{\dR}{\mathrm{dR}} \newcommand{\EKL}{{\mathrm{EKL}}} \newcommand{\Ell}{\mathrm{Ell}} \newcommand{\Fix}{\mathrm{Fix}} \newcommand{\FP}{\mathrm{FP}} \newcommand{\FS}{{ \text{FS} }} \newcommand{\Hasse}{{\mathrm{Hasse}}} \newcommand{\homog}{{ \mathrm{homog} }} \newcommand{\IAS}{\mathrm{IAS}} \newcommand{\KSBA}{\mathrm{KSBA}} \newcommand{\Lat}{\mathrm{Lat}} \newcommand{\LC}{{\mathrm{LC}}} \newcommand{\lci}{\mathrm{lci}} \newcommand{\MHS}{\mathrm{MHS}} \newcommand{\mot}{{ \mathrm{mot}}} \newcommand{\nef}{\mathrm{nef}} \newcommand{\Nil}{{\mathrm{Nil}}} \newcommand{\Nis}{{\mathrm{Nis}}} \newcommand{\Noeth}{{ \mathrm{Noeth} }} \newcommand{\Orb}{{\mathrm{Orb}}} \newcommand{\PD}{\mathrm{PD}} \newcommand{\Pet}{{\mathrm{Pet}}} \newcommand{\QH}{{\mathrm{QH}}} \newcommand{\Quad}{\mathrm{Quad}} \newcommand{\RT}{{\mathrm{RT}}} \newcommand{\SC}{\mathrm{SC}} \newcommand{\slc}{\mathrm{slc}} \newcommand{\SNF}{\mathrm{SNF}} \newcommand{\spinor}{\mathrm{sp}} \newcommand{\tame}{{\mathrm{tame}}} \newcommand{\tb}{\mathrm{tb}} \newcommand{\td}{\mathrm{td}} \newcommand{\tw}{\mathrm{tw}} \newcommand{\VHS}{{\mathrm{VHS} }} \newcommand{\vir}{{\mathrm{vir}}} \newcommand{\VMHS}{\mathrm{VMHS}} \newcommand{\WI}{\mathrm{WI}} \newcommand{\Zar}{{\mathrm{Zar}}} \newcommand{\alev}{{\,\mathrm{a.e.}}} \newcommand{\amp}{{\mathrm{amp}}} \newcommand{\an}{{\mathrm{an}}} \newcommand{\can}{{\mathrm{can}}} \newcommand{\cell}{{ \mathrm{cell}}} \newcommand{\crys}{{\mathrm{crys}}} \newcommand{\cusp}{{ \mathrm{cusp} }} \newcommand{\elliptic}{{\mathrm{ell}}} \newcommand{\ess}{{\mathrm{ess}}} \newcommand{\even}{\text{even}} \newcommand{\fd}{{\mathrm{fd}}} \newcommand{\fg}{{\mathrm{fg}}} \newcommand{\fin}{{\mathrm{fin}}} \newcommand{\free}{{\mathrm{free}}} \newcommand{\ft}{\mathrm{ft}} \newcommand{\hol}{\text{hol}} \newcommand{\holonomy}{{\mathrm{holon}}} \newcommand{\holomorphic}{\text{holo}} \newcommand{\inc}{{\mathrm{inc}}} \newcommand{\irr}{{\mathrm{irr}}} \newcommand{\isotrop}{\mathrm{isotrop}} \newcommand{\lf}{{\mathrm{lf}}} \newcommand{\lft}{\mathrm{lft}} \newcommand{\odd}{\text{odd}} \newcommand{\perf}{{\mathrm{perf}}} \newcommand{\poly}{\mathrm{poly}} \newcommand{\prop}{{\mathrm{prop}}} \newcommand{\qproj}{{\mathrm{qproj}}} \newcommand{\ram}{{\mathrm{ram}}} \newcommand{\red}{{ \text{red} }} \newcommand{\reg}{\mathrm{reg}} \newcommand{\semi}{{\mathrm{semi}}} \newcommand{\semisimple}{{\mathrm{ss}}} \newcommand{\semisimplification}{{\mathrm{ss}}} \newcommand{\sing}{{\mathrm{sing}}} \newcommand{\smol}{{\mathrm{small}}} \newcommand{\snc}{{\mathrm{snc}}} \newcommand{\ss}{{\mathrm{ss}}} \newcommand{\stable}{\mathrm{st}} \newcommand{\std}{\text{std}} \newcommand{\trop}{\mathrm{trop}} \newcommand{\unstable}{\mathrm{unst}} \newcommand{\vamp}{{\mathrm{v.amp}}} \newcommand{\zar}{{\mathrm{zar}}} \newcommand{\ab}{{\operatorname{ab}}} \newcommand{\ad}{{ \operatorname{ad}}} \newcommand{\Ad}{{ \operatorname{Ad} }} \newcommand{\adjoint}{\dagger} \newcommand{\ae}{{ \text{a.e.} }} \newcommand{\afp}{A_{/\FF_p}} \newcommand{\AG}{\operatorname{AG}} \newcommand{\AGL}{\operatorname{AGL}} \newcommand{\AJ}{\operatorname{AJ}} \newcommand{\Alb}{\operatorname{Alb}} \newcommand{\Amp}{{\operatorname{Amp}}} \newcommand{\Ann}{\operatorname{Ann}} \newcommand{\AO}{\operatorname{AO}} \newcommand{\arccot}{\operatorname{arccot}} \newcommand{\arccsc}{\operatorname{arccsc}} \newcommand{\arcsec}{\operatorname{arcsec}} \newcommand{\area}{\operatorname{area}} \newcommand{\Arg}{\operatorname{Arg}} \newcommand{\ASL}{\operatorname{ASL}} \newcommand{\Aut}{\operatorname{Aut}} \newcommand{\Ball}{{B}} \newcommand{\Base}{{ \operatorname{Base}}} \newcommand{\bb}{\operatorname{BB}} \newcommand{\bd}{{\del}} \newcommand{\Betti}{{\operatorname{Betti}}} \newcommand{\BiHol}{\operatorname{BiHol}} \newcommand{\Bil}{\operatorname{Bil}} \newcommand{\Bl}{\operatorname{Bl}} \newcommand{\BM}{{\operatorname{BM}}} \newcommand{\Brauer}{\mathrm{Br}} \newcommand{\Bs}{\operatorname{Bs}} \newcommand{\by}{\times} \newcommand{\candim}{\operatorname{candim}} \newcommand{\Cart}{\operatorname{Cart}} \newcommand{\CDiv}{\operatorname{CDiv}} \newcommand{\CF}{\operatorname{CF}} \newcommand{\CH}{{\operatorname{CH}}} \newcommand{\ch}{\operatorname{ch}} \newcommand{\character}{\operatorname{ch}} \newcommand{\characteristic}{\operatorname{char}} \newcommand{\charpoly}{{\mathrm{charpoly}}} \newcommand{\chern}{{\mathrm{ch}}} \newcommand{\chp}{\operatorname{ch. p}} \newcommand{\Chow}{{\operatorname{Ch}}} \newcommand{\cl}{{ \operatorname{cl}}} \newcommand{\Cl}{\operatorname{Cl}} \newcommand{\CaCl}{\operatorname{CaCl}} \newcommand{\kxnz}{k[x_0, \cdots, x_{n}]} \newcommand{\codom}{\operatorname{codom}} \newcommand{\codim}{\operatorname{codim}} \newcommand{\coev}{\operatorname{coev}} \newcommand{\coh}{\operatorname{coh}} \newcommand{\cohdim}{\operatorname{cohdim}} \newcommand{\coim}{\operatorname{coim}} \newcommand{\coinfl}{\operatorname{coinf}} \newcommand{\coinv}{{\operatorname{coinv}}} \newcommand{\coker}{\operatorname{coker}} \newcommand{\colspace}{\operatorname{colspace}} \newcommand{\compact}{\operatorname{cpt}} \newcommand{\Cone}{{ \mathrm{Cone} }} \newcommand{\cone}{\operatorname{cone}} \newcommand{\Conf}{{\mathrm{Conf}}} \newcommand{\Conj}{{\mathrm{Conj}}} \newcommand{\const}{{\operatorname{const.}}} \newcommand{\cores}{\operatorname{coRes}} \newcommand{\corank}{\operatorname{corank}} \newcommand{\covol}{\operatorname{coVol}} \newcommand{\Cox}{{ \operatorname{Cox} }} \newcommand{\CP}{{\mathbf{CP}}} \newcommand{\Crit}{\operatorname{Crit}} \newcommand{\crit}{\operatorname{crit}} \newcommand{\cross}{\times} \newcommand{\csch}{\operatorname{csch}} \newcommand{\cts}{\text{cts}} \newcommand{\curl}{\operatorname{curl}} \newcommand{\Curv}{\operatorname{Curv}} \newcommand{\Cyl}{{ \mathrm{Cyl} }} \newcommand{\Deck}{\operatorname{Deck}} \newcommand{\ddim}{\operatorname{ddim}} \newcommand{\Def}{\operatorname{Def}} \newcommand{\definedas}{\coloneqq} \newcommand{\del}{{\partial}} \newcommand{\delbar}{{ \bar{\del}}} \newcommand{\depth}{\operatorname{depth}} \newcommand{\Der}{{ \operatorname{Der} }} \newcommand{\det}{\operatorname{det}} \newcommand{\diag}{\operatorname{diag}} \newcommand{\diam}{{\operatorname{diam}}} \newcommand{\Diff}{\operatorname{Diff}} \newcommand{\Diffeo}{{\operatorname{Diffeo}}} \newcommand{\disc}{{\operatorname{disc}}} \newcommand{\discriminant}{{\Delta}} \newcommand{\Disk}{{\operatorname{Disk}}} \newcommand{\Dist}{\operatorname{Dist}} \newcommand{\dist}{\operatorname{dist}} \newcommand{\div}{\operatorname{div}} \newcommand{\Div}{\operatorname{Div}} \newcommand{\dlog}{\operatorname{dLog}} \newcommand{\dom}{\operatorname{dom}} \newcommand{\dP}{{\operatorname{dP}}} \newcommand{\DSt}{{ \operatorname{DSt}}} \newcommand{\Eff}{\operatorname{Eff}} \newcommand{\Emb}{{\operatorname{Emb}}} \newcommand{\En}{{\operatorname{En}}} \newcommand{\Endo}{{ \operatorname{End} }} \newcommand{\eo}{{\operatorname{eo}}} \newcommand{\essdim}{\operatorname{essdim}} \newcommand{\et}{\text{ét}} \newcommand{\Et}{\text{Ét}} \newcommand{\eul}{{\operatorname{eul}}} \newcommand{\ev}{\operatorname{ev}} \newcommand{\exist}{{\exists}} \newcommand{\Exists}{\operatorname{\exists}} \newcommand{\Ext}{\operatorname{Ext}} \newcommand{\EZ}{\operatorname{EZ}} \newcommand{\F}{{\operatorname{F}}} \newcommand{\fet}{\text{fét}} \newcommand{\ff}{\operatorname{ff}} \newcommand{\Fil}{{\operatorname{Fil}}} \newcommand{\Fl}{\operatorname{Fl}} \newcommand{\Flat}{{\operatorname{Flat}}} \newcommand{\Forall}{\operatorname{\forall}} \newcommand{\Forget}{Forget} \newcommand{\fp}{{ \operatorname{fp} }} \newcommand{\fppf}{{\operatorname{fppf}}} \newcommand{\Fppf}{\mathrm{\operatorname{Fppf}}} \newcommand{\fpqc}{{\operatorname{fpqc}}} \newcommand{\Fr}{\operatorname{Fr}} \newcommand{\Frac}{\operatorname{Frac}} \newcommand{\Frame}{\operatorname{Frame}} \newcommand{\Frob}{\operatorname{Frob}} \newcommand{\gal}{{ \operatorname{Gal}}} \newcommand{\gendim}{\operatorname{gendim}} \newcommand{\generic}{{\mathrm{gen}}} \newcommand{\genus}{{\operatorname{gen}}} \newcommand{\GF}{{\mathbf{GF}}} \newcommand{\GL}{\operatorname{GL}} \newcommand{\gp}{{\operatorname{gp} }} \newcommand{\Gr}{{\operatorname{Gr}}} \newcommand{\grad}{\operatorname{grad}} \newcommand{\graded}{\operatorname{gr}} \newcommand{\grdim}{{\operatorname{gr\,dim}}} \newcommand{\Griff}{\operatorname{Griff}} \newcommand{\GU}{\operatorname{GU}} \newcommand{\GW}{{\operatorname{GW}}} \newcommand{\hash}{{\sharp}} \newcommand{\HC}{{\operatorname{HC}}} \newcommand{\hd}{\operatorname{Head}} \newcommand{\he}{\operatorname{h.e.}} \newcommand{\height}{\operatorname{ht}} \newcommand{\HF}{\operatorname{HF}} \newcommand{\HFK}{\operatorname{HFK}} \newcommand{\Hilb}{\operatorname{Hilb}} \newcommand{\hilbdim}{\operatorname{hilbdim}} \newcommand{\Hol}{\operatorname{Hol}} \newcommand{\Hom}{{ \operatorname{Hom} }} \newcommand{\Homcx}{\operatorname{Hom}^{\bullet}} \newcommand{\Homeo}{{\operatorname{Homeo}}} \newcommand{\Honda}{\mathrm{\operatorname{Honda}}} \newcommand{\HP}{{\operatorname{HP}}} \newcommand{\HT}{{\operatorname{HT}}} \newcommand{\hyp}{{\operatorname{hyp}}} \newcommand{\Id}{\operatorname{Id}} \newcommand{\id}{\operatorname{id}} \newcommand{\im}{\operatorname{im}} \newcommand{\Index}{\operatorname{Index}} \newcommand{\Inertia}{{\mathrm{In}}} \newcommand{\infl}{\operatorname{inf}} \newcommand{\Inn}{\operatorname{Inn}} \newcommand{\Intersect}{\bigcap} \newcommand{\Isom}{{\mathrm{Isom}}} \newcommand{\Jac}{\operatorname{Jac}} \newcommand{\jan}{\operatorname{Jan}} \newcommand{\JCF}{\operatorname{JCF}} \newcommand{\Kahler}{\operatorname{Kähler}} \newcommand{\Kl}{\operatorname{Kl}} \newcommand{\ko}{{\operatorname{ko}}} \newcommand{\krulldim}{\operatorname{krulldim}} \newcommand{\ks}{\operatorname{ks}} \newcommand{\Kthree}{\mathrm{K3}} \newcommand{\lcm}{\operatorname{lcm}} \newcommand{\Ld}{\operatorname{{\mathbb{L} }}} \newcommand{\len}{\operatorname{len}} \newcommand{\length}{\operatorname{length}} \newcommand{\LGr}{{\operatorname{LGr}}} \newcommand{\Li}{\mathrm{Li}} \newcommand{\lk}{\operatorname{lk}} \newcommand{\Log}{\operatorname{Log}} \newcommand{\Maps}{\operatorname{Maps}} \newcommand{\mat}{\operatorname{mat}} \newcommand{\Mat}{\operatorname{Mat}} \newcommand{\maxspec}{{\operatorname{maxSpec}}} \newcommand{\MC}{\operatorname{MC}} \newcommand{\MCG}{{\operatorname{MCG}}} \newcommand{\Mero}{\operatorname{Mero}} \newcommand{\mHH}{{\operatorname{HH}}} \newcommand{\minor}{{\operatorname{minor}}} \newcommand{\minpoly}{{\operatorname{minpoly}}} \newcommand{\mod}{\operatorname{mod}} \newcommand{\Mor}{\operatorname{Mor}} \newcommand{\mproj}{\operatorname{mProj}} \newcommand{\mspec}{\operatorname{mSpec}} \newcommand{\MT}{\operatorname{MT}} \newcommand{\mTHH}{{\operatorname{THH}}} \newcommand{\mult}{{\operatorname{mult}}} \newcommand{\MW}{\operatorname{MW}} \newcommand{\nd}{\operatorname{nd}} \newcommand{\NE}{{\operatorname{NE}}} \newcommand{\Nef}{\operatorname{Nef}} \newcommand{\nil}{{\operatorname{nil}}} \newcommand{\Norm}{\operatorname{Nm}} \newcommand{\NS}{{\operatorname{NS}}} \newcommand{\nullity}{\operatorname{nullity}} \newcommand{\nullspace}{\operatorname{nullspace}} \newcommand{\Num}{\operatorname{Num}} \newcommand{\Ob}{{\operatorname{Ob}}} \newcommand{\obs}{\operatorname{obs}} \newcommand{\Obs}{\operatorname{Obs}} \newcommand{\OFrame}{\operatorname{OFrame}} \newcommand{\OGr}{{\operatorname{OGr}}} \newcommand{\Op}{{\operatorname{Op}}} \newcommand{\Ord}{{ \mathrm{Ord} }} \newcommand{\order}{{\operatorname{Ord}}} \newcommand{\oriented}{{ \operatorname{oriented} }} \newcommand{\Orth}{{\operatorname{O}}} \newcommand{\Out}{\operatorname{Out}} \newcommand{\per}{\operatorname{per}} \newcommand{\period}{\operatorname{period}} \newcommand{\PGL}{\operatorname{PGL}} \newcommand{\PHS}{\operatorname{PHS}} \newcommand{\Pic}{\operatorname{Pic}} \newcommand{\Pin}{{\operatorname{Pin}}} \newcommand{\Pl}{\operatorname{Pl}} \newcommand{\Places}{{\operatorname{Places}}} \newcommand{\PO}{{\operatorname{PO}}} \newcommand{\pr}{{\operatorname{pr}}} \newcommand{\prim}{{\operatorname{prim}}} \newcommand{\prin}{\operatorname{prin}} \newcommand{\Prin}{\operatorname{Prin}} \newcommand{\Proj}{\operatorname{Proj}} \newcommand{\projection}{\operatorname{proj}} \newcommand{\PSL}{{\operatorname{PSL}}} \newcommand{\PSU}{{\operatorname{PSU}}} \newcommand{\pt}{{\operatorname{pt}}} \newcommand{\PV}{{ \operatorname{PV} }} \newcommand{\qc}{{\operatorname{qc}}} \newcommand{\QHB}{\operatorname{QHB}} \newcommand{\qst}{{\quad \operatorname{such that} \quad}} \newcommand{\Quot}{\operatorname{Quot}} \newcommand{\radic}{\operatorname{rad}} \newcommand{\Rad}{\operatorname{Rad}} \newcommand{\Ram}{\operatorname{Ram}} \newcommand{\range}{\operatorname{range}} \newcommand{\rank}{\operatorname{rank}} \newcommand{\Rat}{\operatorname{Rat}} \newcommand{\RCF}{\operatorname{RCF}} \newcommand{\Rd}{\operatorname{{\mathbb{R} }}} \newcommand{\Rees}{{\operatorname{Rees}}} \newcommand{\Reg}{\operatorname{Reg}} \newcommand{\Rel}{\operatorname{Rel}} \newcommand{\reldim}{\operatorname{reldim}} \newcommand{\res}{\operatorname{res}} \newcommand{\Res}{\operatorname{Res}} \newcommand{\resultant}{{\mathrm{res}}} \newcommand{\RHom}{\operatorname{\mathbb{R}Hom}} \newcommand{\Ric}{\operatorname{Ric}} \newcommand{\rc}{{\operatorname{rc}}} \newcommand{\rot}{\operatorname{rot}} \newcommand{\rowspace}{\operatorname{rowspace}} \newcommand{\RP}{{\mathbf{RP}}} \newcommand{\RREF}{\operatorname{RREF}} \newcommand{\Sat}{\operatorname{Sat}} \newcommand{\Sec}{\operatorname{Sec}} \newcommand{\sech}{{ \mathrm{sech} }} \newcommand{\selfmap}{{\circlearrowleft}} \newcommand{\Sel}{\operatorname{Sel}} \newcommand{\SF}{\operatorname{SF}} \newcommand{\SGr}{{\operatorname{SGr}}} \newcommand{\sgn}{\operatorname{sgn}} \newcommand{\SHerm}{{\operatorname{SHerm}}} \newcommand{\Sieg}{{\mathrm{Sieg}}} \newcommand{\sign}{\operatorname{sign}} \newcommand{\signature}{\operatorname{sig}} \newcommand{\Sim}{\operatorname{Sim}} \newcommand{\sinc}{\operatorname{sinc}} \newcommand{\Sing}{{\operatorname{Sing}}} \newcommand{\size}{{\sharp}} \newcommand{\SL}{{\operatorname{SL}}} \newcommand{\slope}{{\mathrm{slope}}} \newcommand{\Sm}{{\operatorname{Sm}}} \newcommand{\sm}{\setminus} \newcommand{\smz}{\setminus\theset{0}} \newcommand{\SO}{{\operatorname{SO}}} \newcommand{\soc}{\operatorname{Soc}} \newcommand{\spanof}{\operatorname{span}} \newcommand{\Spc}{\operatorname{Spc}} \newcommand{\Spec}{\operatorname{Spec}} \newcommand{\Spf}{\operatorname{Spf}} \newcommand{\Spin}{{\operatorname{Spin}}} \newcommand{\spinornorm}{{\mathrm{spinornorm}}} \newcommand{\Sq}{\operatorname{Sq}} \newcommand{\sq}{\square} \newcommand{\SSym}{{\operatorname{SSym}}} \newcommand{\Stab}{{\operatorname{Stab}}} \newcommand{\Star}{\operatorname{Star}} \newcommand{\Sub}{{\mathrm{Sub}}} \newcommand{\submfds}{\operatorname{SubMfds}} \newcommand{\SU}{{\operatorname{SU}}} \newcommand{\Sum}{\sum} \newcommand{\supp}{\operatorname{supp}} \newcommand{\Supp}{{\operatorname{Supp}}} \newcommand{\Sw}{{\mathrm{Sw}}} \newcommand{\Syl}{{\operatorname{Syl}}} \newcommand{\Sym}{\operatorname{Sym}} \newcommand{\sym}{\operatorname{Sym}^*} \newcommand{\Symalg}{\sym} \newcommand{\Symb}{\operatorname{Symb}} \newcommand{\Symbil}{\operatorname{SymBil}} \newcommand{\Symp}{{\operatorname{Sp}}} \newcommand{\Tatesymbol}{\operatorname{TateSymb}} \newcommand{\Taut}{\operatorname{Taut}} \newcommand{\TC}{{\operatorname{TC}}} \newcommand{\TCH}{{\operatorname{TCH}}} \newcommand{\Th}{\operatorname{Th}} \newcommand{\THC}{{\operatorname{THC}}} \newcommand{\thinrank}{T_n\dash\operatorname{rank}} \newcommand{\Todd}{\operatorname{Td}} \newcommand{\Tor}{\operatorname{Tor}} \newcommand{\tors}{{\operatorname{tors}}} \newcommand{\Tot}{{ \operatorname{Tot} }} \newcommand{\TP}{{\operatorname{TP}}} \newcommand{\tr}{{\mathrm{tr}}} \newcommand{\Tr}{\operatorname{Tr}} \newcommand{\trace}{\operatorname{tr}} \newcommand{\Trace}{\operatorname{Trace}} \newcommand{\trdeg}{{\mathrm{trdeg}}} \newcommand{\transfer}{\operatorname{transfer}} \newcommand{\triv}{\operatorname{triv}} \newcommand{\Triv}{\operatorname{Triv}} \newcommand{\tspt}{{\{\operatorname{pt}\}}} \newcommand{\txand}{{\operatorname{ and }}} \newcommand{\txor}{{\operatorname{ or }}} \newcommand{\type}{{\operatorname{type}}} \newcommand{\U}{{\operatorname{U}}} \newcommand{\UFrame}{\operatorname{UFrame}} \newcommand{\unital}{{\operatorname{unital}}} \newcommand{\Union}{\bigcup} \newcommand{\unram}{{\scriptscriptstyle\mathrm{un}}} \newcommand{\USp}{{\operatorname{USp}}} \newcommand{\val}{{\operatorname{val}}} \newcommand{\Verts}{{ \operatorname{Verts} }} \newcommand{\vol}{\operatorname{vol}} \newcommand{\volume}{\operatorname{Vol}} \newcommand{\Vor}{\operatorname{Vor}} \newcommand{\WDiv}{\operatorname{WDiv}} \newcommand{\WP}{{\mathbf{WP}}} \newcommand{\Wedge}{\bigwedge} \newcommand{\weight}{{ \operatorname{weight} }} \newcommand{\Wittvectors}{{\mathbb{W}}} \newcommand{\wt}{{\operatorname{wt}}} \newcommand{\zbar}{\bar{z}} \newcommand{\ZHB}{\operatorname{ZHB}} \newcommand{\Ag}{{\mathcal{A}_g}} \newcommand{\agbar}{\bar{\Ag}} \newcommand{\Ahat}{\hat{ \operatorname{A}}_g} \newcommand{\B}{{\mathbf{B}}} \newcommand{\bmgn}{{ \bar{\mathcal{M}}_{g, n} }} \newcommand{\boxtensor}{\boxtimes} \newcommand{\Cc}{{\check{C}}} \newcommand{\cechH}{{\check{H}}} \newcommand{\coind}{\operatorname{coInd}} \newcommand{\D}{{ \mathsf{D} }} \newcommand{\dualnumbers}{{ [\eps] / \eps^2 }} \newcommand{\E}{{\mathbf{E}}} \newcommand{\fracId}{{ \ddot{\Id} }} \newcommand{\G}{{\mathsf{G}}} \newcommand{\hocolim}{\operatorname{hocolim}} \newcommand{\HZ}{{H\ZZ}} \newcommand{\I}{\mathrm{I}} \newcommand{\II}{\mathrm{II}} \newcommand{\III}{\mathrm{III}} \newcommand{\intcl}{\operatorname{cl}^{\mathrm{int}}} \newcommand{\algcl}{\operatorname{cl}^{\mathrm{alg}}} \newcommand{\sepcl}{\operatorname{cl}^{\mathrm{sep}}} \newcommand{\iso}{\isomorphic} \newcommand{\IV}{\mathrm{IV}} \newcommand{\K}{{\mathsf{K}}} \newcommand{\kbar}{{ \overline{k} }} \newcommand{\kfq}{K_{/\FF_q}} \newcommand{\KH}{\K^{\scriptscriptstyle \mathrm{H}}} \newcommand{\KM}{\K^{\scriptstyle\mathrm{M}}} \newcommand{\KMimp}{\hat{\K}^{\scriptscriptstyle \mathrm{M}}} \newcommand{\KMW}{\K^{\scriptscriptstyle \mathrm{MW}}} \newcommand{\ksep}{\sepclosure{k}} \newcommand{\lderive}{\leftderive} \newcommand{\leftderive}{{\mathbf{L}}} \newcommand{\liealgk}{{ \liealg_{/k} }} \newcommand{\lkt}{{L_{\mathrm{K3}}}} \newcommand{\lktcc}{{L_{\mathrm{K3}, \CC}}} \newcommand{\lkttd}{{L_{\mathrm{K3}, 2d}}} \newcommand{\Ltensor}{\overset{\mathbb{L}}{ \otimes}} \newcommand{\mbar}{\bar{\mathcal{M}}} \newcommand{\Mg}{{\mathcal{M}_g}} \newcommand{\mg}{{ \mathcal{M}_{g} }} \newcommand{\Mgbar}{\bar{\Mg}} \newcommand{\Mgn}{{ \mathcal{M}_{g, n} }} \newcommand{\Mell}{{ \mathcal{M}_{\mathrm{ell}} }} \newcommand{\mH}{{ \mathsf{H} }} \newcommand{\mviso}{{\mapsvia{\sim}}} \newcommand{\OX}{{\mathcal{O}_X}} \newcommand{\Presh}{\presh} \newcommand{\Prod}{\displaystyle\prod} \newcommand{\primetop}{{\scriptscriptstyle \mathrm{prime-to-}p}} \newcommand{\ptd}{{\scriptstyle { \ast } }} \newcommand{\qiso}{\homotopic} \newcommand{\rderive}{\rightderive} \newcommand{\resprod}{\prod^{\res}} \newcommand{\restensor}{\bigotimes^{\res}} \newcommand{\rightderive}{{\mathbf{R}}} \newcommand{\rrarrows}{\rightrightarrows} \newcommand{\sdot}{{ \mathsf{S}_{\cdot} }} \newcommand{\Sgn}{{ \Sigma_{g, n} }} \newcommand{\shriek}{{ ! }} \newcommand{\Spinc}{\mathrm{Spin}^{{ \scriptscriptstyle \mathbf C} }} \newcommand{\T}{{\mathbf{T}}} \newcommand{\Tensor}{\bigotimes} \newcommand{\tensor}{\otimes} \newcommand{\tgn}{{ \mathcal{T}_{g, n} }} \newcommand{\TM}{{\T M}} \newcommand{\Totprod}{\Tot^{\Pi}} \newcommand{\Totsum}{\Tot^{\oplus}} \newcommand{\TX}{{\T X}} \newcommand{\Ug}{{\mathcal{U}(\mathfrak{g}) }} \newcommand{\Uh}{{\mathcal{U}(\mathfrak{h}) }} \newcommand{\V}{{\textrm{V}}} \newcommand{\VI}{{\textrm{VI}}} \newcommand{\wdot}{{ \mathsf{w}_{\cdot} }} \newcommand{\Wedgepower}{\bigwedge\nolimits} \newcommand{\Xff}{{X_\mathrm{FF}}} \newcommand{\xpn}{{ x^{p^n} }} \newcommand{\ZHS}{\ZZ\operatorname{HS}} \newcommand{\ZVHS}{{ \ZZ\mathrm{VHS} }} \newcommand{\abuts}{\Rightarrow} \newcommand{\actson}{\curvearrowright} \newcommand{\actsonl}{\curvearrowleft} \newcommand{\asymptotic}{\ll} \newcommand{\capprod}{\frown} \newcommand{\containing}{\supseteq} \newcommand{\convolve}{\ast} \newcommand{\coveredby}{\leftleftarrows} \newcommand{\covers}{\rightrightarrows} \newcommand{\covariant}{\nabla} \newcommand{\cupprod}{\smile} \newcommand{\dash}{{\hbox{-}}} \newcommand{\decreasesto}{\searrow} \newcommand{\disjoint}{{\amalg}} \newcommand{\Disjoint}{\bigsqcup} \newcommand{\divergence}{{ \nabla\cdot }} \newcommand{\divides}{\mathrel{|}} \newcommand{\notdivides}{\nmid} \newcommand{\dV}{\,dV} \newcommand{\dalpha}{\,d\alpha} \newcommand{\dA}{\,dA} \newcommand{\dm}{\,dm} \newcommand{\dmu}{\,d\mu} \newcommand{\dn}{\,dn} \newcommand{\dphi}{\,d\phi} \newcommand{\dr}{\,dr} \newcommand{\drho}{\,d\rho} \newcommand{\ds}{\displaystyle} \newcommand{\dt}{\,dt} \newcommand{\dtau}{\,d\tau} \newcommand{\dtheta}{\,d\theta} \newcommand{\du}{\,du} \newcommand{\dw}{\,dw} \newcommand{\dx}{\,dx} \newcommand{\dxi}{\,d\xi} \newcommand{\dy}{\,dy} \newcommand{\dz}{\,dz} \newcommand{\dzbar}{\,d\bar{z}} \newcommand{\dzeta}{\,d\zeta} \newcommand{\embeds}{\hookrightarrow} \newcommand{\embedsdense}{{ \underset{ {\scriptscriptstyle\mathrm{dense}} }{\hookrightarrow} }} \newcommand{\eps}{{\varepsilon}} \newcommand{\freeprod}{\ast} \newcommand{\from}{\leftarrow} \newcommand{\gon}{{\dash\mathrm{gon}}} \newcommand{\gradient}{\nabla} \newcommand{\hodgestar}{\star} \newcommand{\homotopic}{\simeq} \newcommand{\hq}{{/}} \newcommand{\increasesto}{\nearrow} \newcommand{\injects}{\hookrightarrow} \newcommand{\injectivelim}{\varinjlim} \newcommand{\colim}{\operatorname*{colim}} \newcommand{\injectsfrom}{\hookleftarrow} \newcommand{\injresolve}{\leftleftarrows} \newcommand{\intersect}{\cap} \newcommand{\into}{\to} \newcommand{\iscontainedin}{\subseteq} \newcommand{\isomorphic}{{ \, \mapsvia{\sim}\, }} \newcommand{\join}{{ \ast }} \newcommand{\laplacian}{\Delta} \newcommand{\mapbackforth}{\operatorname*{\rightleftharpoons}} \newcommand{\mapstofrom}{\rightleftharpoons} \newcommand{\modmod}{\gitquot} \newcommand{\htyquot}{\gitquot} \newcommand{\normal}{{~\trianglelefteq~}} \newcommand{\normalizer}{{ N }} \newcommand{\notimplies}{\centernot\implies} \newcommand{\ofrom}{\overset{\circ}{\leftarrow}} \newcommand{\onto}{\twoheadhthtarrow} \newcommand{\oto}{\overset{\circ}{\rightarrow}} \newcommand{\padic}{p\dash\text{adic}} \newcommand{\plocal}{{ \scriptsize {}_{ \localize{p} } }} \newcommand{\projectivelim}{\varprojlim} \newcommand{\projresolve}{\rightrightarrows} \newcommand{\proportional}{\propto} \newcommand{\qed}{\hfill\ensuremath{\blacksquare}} \newcommand{\rational}{\rationalmap} \newcommand{\rationalmap}{\dashrightarrow} \newcommand{\semidirect}{\rtimes} \newcommand{\st}{{~\mathrel{\Big\vert}~}} \newcommand{\suchthat}{\st} \newcommand{\surjects}{\twoheadrightarrow} \newcommand{\too}{\longrightarrow} \newcommand{\transverse}{\pitchfork} \newcommand{\uniformlyconverges}{\rightrightarrows} \newcommand{\union}{\cup} \newcommand{\unioninfty}{{\union\theset{\infty}}} \newcommand{\up}{\uparrow} \newcommand{\wait}{{-}} \newcommand{\wedgeprod}{\vee} \newcommand{\wreath}{\wr} \newcommand{\bA}{{\mathbb{A}}} \newcommand{\bB}{{\mathbb{B}}} \newcommand{\bC}{{\mathbb{C}}} \newcommand{\bD}{{\mathbb{D}}} \newcommand{\bE}{{\mathbb{E}}} \newcommand{\bF}{{\mathbb{F}}} \newcommand{\bG}{{\mathbb{G}}} \newcommand{\bH}{{\mathbb{H}}} \newcommand{\bI}{{\mathbb{I}}} \newcommand{\bJ}{{\mathbb{J}}} \newcommand{\bK}{{\mathbb{K}}} \newcommand{\bL}{{\mathbb{L}}} \newcommand{\bM}{{\mathbb{M}}} \newcommand{\bN}{{\mathbb{N}}} \newcommand{\bO}{{\mathbb{O}}} \newcommand{\bP}{{\mathbb{P}}} \newcommand{\bQ}{{\mathbb{Q}}} \newcommand{\bR}{{\mathbb{R}}} \newcommand{\bS}{{\mathbb{S}}} \newcommand{\bT}{{\mathbb{T}}} \newcommand{\bU}{{\mathbb{U}}} \newcommand{\bV}{{\mathbb{V}}} \newcommand{\bW}{{\mathbb{W}}} \newcommand{\bX}{{\mathbb{X}}} \newcommand{\bY}{{\mathbb{Y}}} \newcommand{\bZ}{{\mathbb{Z}}} \newcommand{\mfA}{{\mathfrak{A}}} \newcommand{\mfB}{{\mathfrak{B}}} \newcommand{\mfD}{{\mathfrak{D}}} \newcommand{\mfE}{{\mathfrak{E}}} \newcommand{\mfG}{{\mathfrak{G}}} \newcommand{\mfH}{{\mathfrak{H}}} \newcommand{\mfI}{{\mathfrak{I}}} \newcommand{\mfJ}{{\mathfrak{J}}} \newcommand{\mfK}{{\mathfrak{K}}} \newcommand{\mfL}{{\mathfrak{L}}} \newcommand{\mfM}{{\mathfrak{M}}} \newcommand{\mfN}{{\mathfrak{N}}} \newcommand{\mfO}{{\mathfrak{O}}} \newcommand{\mfP}{{\mathfrak{P}}} \newcommand{\mfQ}{{\mathfrak{Q}}} \newcommand{\mfR}{{\mathfrak{R}}} \newcommand{\mfT}{{\mathfrak{T}}} \newcommand{\mfU}{{\mathfrak{U}}} \newcommand{\mfV}{{\mathfrak{V}}} \newcommand{\mfW}{{\mathfrak{W}}} \newcommand{\mfY}{{\mathfrak{Y}}} \newcommand{\mfZ}{{\mathfrak{Z}}} \newcommand{\hA}{{\widehat{A}}} \newcommand{\hB}{{\widehat{B}}} \newcommand{\hC}{{\widehat{C}}} \newcommand{\hD}{{\widehat{D}}} \newcommand{\hE}{{\widehat{E}}} \newcommand{\hF}{{\widehat{F}}} \newcommand{\hG}{{\widehat{G}}} \newcommand{\hH}{{\widehat{H}}} \newcommand{\hI}{{\widehat{I}}} \newcommand{\hJ}{{\widehat{J}}} \newcommand{\hK}{{\widehat{K}}} \newcommand{\hL}{{\widehat{L}}} \newcommand{\hM}{{\widehat{M}}} \newcommand{\hN}{{\widehat{N}}} \newcommand{\hO}{{\widehat{O}}} \newcommand{\hP}{{\widehat{P}}} \newcommand{\hQ}{{\widehat{Q}}} \newcommand{\hR}{{\widehat{R}}} \newcommand{\hS}{{\widehat{S}}} \newcommand{\hT}{{\widehat{T}}} \newcommand{\hU}{{\widehat{U}}} \newcommand{\hV}{{\widehat{V}}} \newcommand{\hW}{{\widehat{W}}} \newcommand{\hX}{{\widehat{X}}} \newcommand{\hY}{{\widehat{Y}}} \newcommand{\hZ}{{\widehat{Z}}} \newcommand{\wA}{{\widetilde{A}}} \newcommand{\wB}{{\widetilde{B}}} \newcommand{\wC}{{\widetilde{C}}} \newcommand{\wD}{{\widetilde{D}}} \newcommand{\wE}{{\widetilde{E}}} \newcommand{\wF}{{\widetilde{F}}} \newcommand{\wG}{{\widetilde{G}}} \newcommand{\wH}{{\widetilde{H}}} \newcommand{\wI}{{\widetilde{I}}} \newcommand{\wJ}{{\widetilde{J}}} \newcommand{\wK}{{\widetilde{K}}} \newcommand{\wL}{{\widetilde{L}}} \newcommand{\wM}{{\widetilde{M}}} \newcommand{\wN}{{\widetilde{N}}} \newcommand{\wO}{{\widetilde{O}}} \newcommand{\wP}{{\widetilde{P}}} \newcommand{\wQ}{{\widetilde{Q}}} \newcommand{\wR}{{\widetilde{R}}} \newcommand{\wS}{{\widetilde{S}}} \newcommand{\wT}{{\widetilde{T}}} \newcommand{\wU}{{\widetilde{U}}} \newcommand{\wV}{{\widetilde{V}}} \newcommand{\wW}{{\widetilde{W}}} \newcommand{\wX}{{\widetilde{X}}} \newcommand{\wY}{{\widetilde{Y}}} \newcommand{\wZ}{{\widetilde{Z}}} \newcommand{\oA}{{\overline{A}}} \newcommand{\oB}{{\overline{B}}} \newcommand{\oC}{{\overline{C}}} \newcommand{\oD}{{\overline{D}}} \newcommand{\oE}{{\overline{E}}} \newcommand{\oF}{{\overline{F}}} \newcommand{\oG}{{\overline{G}}} \newcommand{\oH}{{\overline{H}}} \newcommand{\oI}{{\overline{I}}} \newcommand{\oJ}{{\overline{J}}} \newcommand{\oK}{{\overline{K}}} \newcommand{\oL}{{\overline{L}}} \newcommand{\oM}{{\overline{M}}} \newcommand{\oN}{{\overline{N}}} \newcommand{\oO}{{\overline{O}}} \newcommand{\oP}{{\overline{P}}} \newcommand{\oQ}{{\overline{Q}}} \newcommand{\oR}{{\overline{R}}} \newcommand{\oS}{{\overline{S}}} \newcommand{\oT}{{\overline{T}}} \newcommand{\oU}{{\overline{U}}} \newcommand{\oV}{{\overline{V}}} \newcommand{\oW}{{\overline{W}}} \newcommand{\oX}{{\overline{X}}} \newcommand{\oY}{{\overline{Y}}} \newcommand{\oZ}{{\overline{Z}}} \newcommand{\uA}{{\underline{A}}} \newcommand{\uB}{{\underline{B}}} \newcommand{\uC}{{\underline{C}}} \newcommand{\uD}{{\underline{D}}} \newcommand{\uE}{{\underline{E}}} \newcommand{\uF}{{\underline{F}}} \newcommand{\uG}{{\underline{G}}} \newcommand{\uH}{{\underline{H}}} \newcommand{\uI}{{\underline{I}}} \newcommand{\uJ}{{\underline{J}}} \newcommand{\uK}{{\underline{K}}} \newcommand{\uL}{{\underline{L}}} \newcommand{\uM}{{\underline{M}}} \newcommand{\uN}{{\underline{N}}} \newcommand{\uO}{{\underline{O}}} \newcommand{\uP}{{\underline{P}}} \newcommand{\uQ}{{\underline{Q}}} \newcommand{\uR}{{\underline{R}}} \newcommand{\uS}{{\underline{S}}} \newcommand{\uT}{{\underline{T}}} \newcommand{\uU}{{\underline{U}}} \newcommand{\uV}{{\underline{V}}} \newcommand{\uW}{{\underline{W}}} \newcommand{\uX}{{\underline{X}}} \newcommand{\uY}{{\underline{Y}}} \newcommand{\uZ}{{\underline{Z}}} \newcommand{\Co}{{\mathrm{Co}}} \newcommand{\Nik}{{\mathrm{Nik}}} \newcommand{\Nod}{{\mathrm{Nod}}} \newcommand{\latI}{\mathrm{I}} \newcommand{\latII}{\mathrm{II}} \newcommand{\lEn}{L_{\mathrm{En}}} \newcommand{\lEnII}{{\mathrm{II}}_{1, 9}} \newcommand{\lias}{L_{\mathrm{IAS}}} \newcommand{\liasplus}{\lias^+} \newcommand{\liasminus}{\lias^-} \newcommand{\rhok}{\rho_{\mathrm{K3}}} \newcommand{\rhoias}{\rho_{\mathrm{IAS}}} \newcommand{\utor}{^{\mathrm{tor}}} \newcommand{\dnor}{_{\mathrm{nor}}} \newcommand{\fco}{F_{\Co}} \newcommand{\fell}{F_{ \mathrm{ell} }} \newcommand{\fen}{F_{\En}} \newcommand{\fentwo}{F_{\En,2}} \newcommand{\ftd}{F_{2d}} \newcommand{\fttz}{F_{(2,2,0)}} \newcommand{\ofco}{\overline{F}_{\Co}} \newcommand{\ofen}{\overline{F}_{\En}} \newcommand{\ofentwo}{\overline{F}_{\En,2}} \newcommand{\ofttz}{\overline{F}_{(2,2,0)}} \newcommand{\ten}{T_{\En}} \newcommand{\tdp}{T_{\dP}} \newcommand{\sdp}{S_{\dP}} \newcommand{\sen}{S_{\En}} \newcommand{\gdp}{{\Gamma_{\dP}}} \newcommand{\gent}{{\Gamma_{\En, 2}}} \newcommand{\gell}{\Gamma^{ \mathrm{ell} }} \newcommand{\tell}{T_{ \mathrm{ell} }} \newcommand{\idp}{\iota_{\dP}} \newcommand{\ien}{\iota_{\En}} \newcommand{\Idp}{I_{\dP}} \newcommand{\Ien}{I_{\En}} \newcommand{\inik}{\iota_{ \Nik }} \newcommand{\Inik}{I_{ \Nik }} \newcommand{\ienzero}{\iota_{\En, 0}} \newcommand{\gref}{\Gamma\dref} \newcommand{\dref}{_{\rm r}} \newcommand{\OrthObs}{\Orth_*} \newcommand{\ADE}{\mathrm{ADE}} \newcommand{\ADEBC}{\mathrm{ADE}+\mathrm{BC}} \newcommand{\tADE}{\widetilde{ \ADE }} \newcommand{\Bir}{\operatorname{Bir}} \newcommand{\Conv}{\operatorname{Conv}} \newcommand{\Exc}{\operatorname{Exc}} \newcommand{\GCD}{\operatorname{GCD}} \newcommand{\M}{\operatorname{M}} \newcommand{\Projm}{\operatorname{Projm}} \newcommand{\Specm}{\operatorname{Specm}} \newcommand{\Ver}{\operatorname{Ver}} \newcommand{\isoto}{\xrightarrow{\sim}} \newcommand{\wh}{\widehat} \newcommand{\la}{\langle} \newcommand{\ra}{\rangle} \newcommand{\lrc}{\lrcorner} \newcommand{\llc}{\llcorner} \newcommand{\urc}{\urcorner} \newcommand{\ulc}{\ulcorner} \newcommand{\uopp}{^{\rm opp}} \newcommand{\ubb}{^{\rm BB}} \newcommand{\dto}{\Rightarrow} \newcommand{\fign}{Fig.~\ref{fig:discforms}} \newcommand{\hoV}{\widehat{\overline V}} \newcommand{\hoD}{\widehat{\overline D}} \newcommand{\ooT}{\overline{\overline T}} \newcommand{\ias}{\operatorname{IAS}^2} \newcommand{\lge}{_{\ge0}} \newcommand{\ocC}{\overline{\mcc}} \newcommand{\lred}{_{\rm red}} \newcommand{\mr}{\bar r} \newcommand{\ma}{\bar a} \newcommand{\mdelta}{\bar \delta} \newcommand{\mk}{\bar k} \newcommand{\me}{\hat e} \newcommand{\miota}{\hat \iota} \newcommand{\oPic}{\overline{\Pic}} \newcommand{\ucox}{^{\rm cox}} \newcommand{\lir}{_{\rm ir}} \newcommand{\usat}{^{\rm sat}} \newcommand{\Cur}{\operatorname{Cur}} \newcommand{\ohV}{\overline{\hV}} \newcommand{\dgen}{_{\rm gen}} \newcommand{\dmon}{_{\rm mon}} \newcommand{\dias}{_{\rm IAS}} \newcommand{\dram}{_{\rm ram}} \newcommand{\drel}{_{\rm rel}} \newcommand{\dirr}{_{\rm irr}} \newcommand{\vrel}{V\drel} \newcommand{\virr}{V\dirr} \newcommand{\wref}{W\dref} \newcommand{\chref}{\ch\dref} \newcommand{\fref}{\mfF\dref} \newcommand{\fram}{\mfF\dram} \newcommand{\relpart}{\operatorname{rel}} \newcommand{\irrpart}{\operatorname{irr}} \newcommand{\fcref}{\mfC\dref} \newcommand{\fgen}{\mfF_{\rm gen}} \newcommand{\fsfref}{\mfF_S^{\fref}} \newcommand{\ofsfref}{\oF_S^{\fref}} \newcommand{\upar}{^{\rm par}} \newcommand{\dleft}{{}_{\rm left}} \newcommand{\dright}{{}_{\rm right}} \newcommand{\evn}{\text{even }n} \newcommand{\odn}{\text{odd }n} \newcommand{\BB}{\operatorname{BB}} \newcommand{\ConvOp}{\operatorname{Conv}} \newcommand{\perfOp}{\operatorname{perf}} \newcommand{\GIT}{\operatorname{GIT}} \newcommand{\isoGr}{\operatorname{IsoGr}} \newcommand{\FG}{F_\Gamma} \newcommand{\IA}{\mathrm{IA}} \newcommand{\IAD}{\mathrm{IAD}} \newcommand{\IARP}{\mathrm{IARP}} \newcommand{\OStab}{\Orth^*} \newcommand{\ZZtwoadic}{\ZZ_{\hat 2}} \newcommand{\cox}{\Cox} \newcommand{\irrelevant}{\mathrm{irr}} \newcommand{\relevant}{\mathrm{rel}} \newcommand{\rcop}{\mathrm{rc}} \newcommand{\opop}{\mathrm{op}} \newcommand{\liek}{\mathfrak{k}} \newcommand{\liev}{\mathfrak{v}} \newcommand{\tiling}{\mathcal{T}} \newcommand{\weylgroup}{\mathcal{W}} \newcommand{\diverge}{\uparrow} \newcommand{\uksba}{^{\mathrm{KSBA}}} \newcommand{\uktriv}{^{K\text{-}\mathrm{triv}}} \newcommand{\textand}{\text{ and }} \newcommand{\textelse}{\text{ otherwise }} \newcommand{\textfor}{\text{ for }} \newcommand{\textif}{\text{ if }} \newcommand{\textor}{\text{ or }} \newcommand{\where}{\text{ where }} \newcommand{\Poincare}{Poincar\'e} \newcommand{\Bbb}{\mathbb} \newcommand{\HalphenInvariants}{(10, 10, 1)} \newcommand{\EnriquesInvariants}{(10, 10, 0)} \newcommand{\abs}[1]{{\left\lvert {#1} \right\rvert}} \newcommand{\norm}[1]{{\left\lVert {#1} \right\rVert}} \newcommand{\normm}[1]{{\left\lVert \left\lVert {#1} \right\rVert\right\rVert}} \newcommand{\pnorm}[2]{{\left\lVert {#1} \right\rVert}_{#2}} \newcommand{\matt}[4]{{ \begin{bmatrix} {#1} & {#2} \\ {#3} & {#4} \end{bmatrix} }} \newcommand{\adjoin}[1]{{ \left[ \scriptstyle {#1} \right] }} \newcommand{\polynomialring}[1]{{ \left[ {#1} \right] }} \newcommand{\bracket}[1]{\left\langle #1 \right\rangle} \newcommand{\generators}[1]{\left\langle{#1}\right\rangle} \newcommand{\sqgens}[1]{\left[ {#1} \right]} \newcommand{\freeon}[1]{\left[ {#1} \right]} \newcommand{\dgens}[1]{\generators{\generators{ #1 }}} \newcommand{\ceiling}[1]{{\left\lceil #1 \right\rceil}} \newcommand{\floor}[1]{{\left\lfloor #1 \right\rfloor}} \newcommand{\bicomplex}[1]{{ {#1}_{\scriptscriptstyle \bullet, \bullet}}} \newcommand{\cobicomplex}[1]{{ {#1}^{\scriptscriptstyle \bullet, \bullet}}} \newcommand{\cocomplex}[1]{{ {#1}^{\scriptscriptstyle \bullet}}} \newcommand{\complex}[1]{{ {#1}_{\scriptscriptstyle \bullet}}} \newcommand{\decfiltration}[1]{{#1}_{\bullet}} \newcommand{\incfiltration}[1]{{#1}^{\bullet}} \newcommand{\ctz}[1]{\, {{\converges{{#1} \to\infty}\longrightarrow 0}} \,} \newcommand{\fps}[1]{{\llbracket #1 \rrbracket }} \newcommand{\formalpowerseries}[1]{\fps{#1}} \newcommand{\functionfield}[1]{{ \left( {#1} \right) }} \newcommand{\rff}[1]{\functionfield{#1}} \newcommand{\htyclass}[1]{{ \left[ {#1} \right] }} \newcommand{\ideal}[1]{\mathcal{#1}} \newcommand{\inner}[2]{{\left\langle {#1},~{#2} \right\rangle}} \newcommand{\invert}[1]{{ \left[ { \scriptstyle \frac{1}{#1} } \right] }} \newcommand{\localize}[1]{\left[ { \scriptstyle \inverseof{#1} } \right]} \newcommand{\plocalize}[1]{\primelocalize{#1}} \newcommand{\primelocalize}[1]{\left[ { \scriptstyle \inverseof{({#1}^c)} } \right]} \newcommand{\fls}[1]{(\hspace{-0.25em}( #1 )\hspace{-0.22em})} \newcommand{\laurentseries}[1]{\fls{#1}} \newcommand{\embedsvia}[1]{\xhookrightarrow{#1}} \newcommand{\open}[1]{\overset{\circ}{#1}} \newcommand{\poisbrack}[2]{{\left\{ {#1},~{#2} \right\} }} \newcommand{\dcoset}[3]{{#1}\mkern-3mu\diagdown\mkern-3mu{}^{#2}\mkern-3mu\diagup\mkern-3mu{#3}} \newcommand{\dcosetl}[2]{{#1}\mkern-3mu\diagdown\mkern-3mu{}^{#2}} \newcommand{\dcosetr}[2]{{#1}\mkern-3mu\diagup\mkern-3mu{#2}} \newcommand{\leftquotient}[2]{{#1}\mkern-3mu\diagdown\mkern-3mu{}^{#2}} \newcommand{\gitquot}{\mathbin{/\!/}} \newcommand{\jacobsonrad}[1]{{J ({#1}) }} \newcommand{\nilrad}[1]{{\sqrt{0_{#1}} }} \newcommand{\Restriction}[2]{\mathrm{Res}^{#1}_{#2}} \newcommand{\coRestriction}[2]{\mathrm{coRes}^{#1}_{#2}} \newcommand{\Induction}[2]{\mathrm{Ind}^{#1}_{#2}} \newcommand{\coInduction}[2]{\mathrm{coInd}^{#1}_{#2}} \newcommand{\sheafify}[1]{\left( #1 \right)^{\scriptscriptstyle \mathrm{sh}}} \newcommand{\complete}[1]{{ {}_{ \hat{#1} } }} \newcommand{\takecompletion}[1]{{ \overbrace{#1}^{\widehat{\hspace{4em}}} }} \newcommand{\kv}{{ k_{\hat{v}} }} \newcommand{\Lv}{{ L_{\hat{v}} }} \newcommand{\coslice}[1]{_{{#1/}}} \newcommand{\liesover}[1]{{ {}_{/ {#1}} }} \newcommand{\slice}[1]{_{/ {#1}}} \newcommand{\symb}[2]{{ \qty{ #1 \over #2 } }} \newcommand{\tl}[2]{{ #1_1, \cdots, #1_{#2} }} \newcommand{\tlset}[2]{\theset{ {#1}_{1}, \cdots, {#1}_{#2} }} \newcommand{\tlz}[2]{{ #1_0, \cdots, #1_{#2} }} \newcommand{\tsl}[3]{\theset{ {#1}_{#2}, \cdots, {#1}_{#3} }} \newcommand{\fourier}[1]{\widehat{#1}} \newcommand{\cartpower}[1]{{ {}^{ \scriptscriptstyle\times^{#1} } }} \newcommand{\disjointpower}[2]{{#1}^{\scriptscriptstyle\coprod^{#2}}} \newcommand{\derivedtensorpower}[3]{{ {}^{ \scriptstyle {}_{#1} {\otimes_{#2}^{#3}} } }} \newcommand{\fiberpower}[3]{{#1}^{\scriptscriptstyle\fiberproduct{#2}^{#3}}} \newcommand{\powers}[1]{{ {}^{\cdot #1} }} \newcommand{\prodpower}[2]{{#1}^{\scriptscriptstyle\times^{#2}}} \newcommand{\skel}[1]{{ {}^{ (#1) } }} \newcommand{\smashpower}[2]{{#1}^{\scriptscriptstyle\smashprod^{#2}}} \newcommand{\sumpower}[1]{{ {}^{ \oplus{#1} } }} \newcommand{\tensorpower}[2]{{ {}^{ \scriptstyle\otimes_{#1}^{#2} } }} \newcommand{\tensorpowerk}[2]{{#1}^{\scriptscriptstyle\otimes_{k}^{#2}}} \newcommand{\transp}[1]{{ \, {}^{t}{ \left( #1 \right) } }} \newcommand{\wedgepower}[2]{{#1}^{\scriptscriptstyle\smashprod^{#2}}} \newcommand{\twistleft}[2]{{ {}^{#1} #2 }} \newcommand{\twistright}[2]{{ #2 {}^{#1} }} \newcommand{\globsec}[1]{{\Gamma\qty{#1} }} \newcommand{\addbase}[1]{{ {}_{pt} }} \newcommand{\catspan}[3]{\roof{#1}{#2}{#3}} \newcommand{\cptf}[1]{\overline{ #1 }} \newcommand{\cpt}[1]{\overline{#1}} \newcommand{\normalize}[1]{{#1}^{\nu}} \newcommand{\ksbacpt}[1]{\cpt{#1}^{\operatorname{KSBA}}} \newcommand{\normksbacpt}[1]{\normalize{ \cpt{#1} }} \newcommand{\bbcpt}[1]{\cpt{#1}^{ \operatorname{BB} }} \newcommand{\gitcpt}[1]{\cpt{#1}^{ \operatorname{GIT} }} \newcommand{\semifan}[1]{\mathcal{#1}} \newcommand{\semifans}[1]{\semifan{#1}_{\bullet}} \newcommand{\semitorfan}{\semifans{F}} \newcommand{\semitorcpt}[1]{\cpt{#1}^{\semitorfan}} \newcommand{\semifancpt}[2]{\cpt{#1}^{#2}} \newcommand{\torfan}{\Sigma} \newcommand{\torfans}{\torfan_{\bullet}} \newcommand{\torcpt}[1]{\semifancpt{#1}{ \torfans }} \newcommand{\coxfan}{\torfan^{\operatorname{Cox}}} \newcommand{\coxfans}{\torfans^{\operatorname{Cox}}} \newcommand{\coxcpt}[1]{\semifancpt{#1}{\coxfans}} \newcommand{\BBfan}{\Sigma^{\operatorname{BB}}} \newcommand{\halfpd}[1]{D_{#1}} \newcommand{\fullpd}[1]{\Omega_{#1}} \newcommand{\dmodgamma}[2]{{#1}/{#2}} \newcommand{\discgroup}[1]{A_{#1}} \newcommand{\diverges}{\mapstofrom} \newcommand{\langL}[1]{{}^{L}{#1}} \newcommand{\modulo}{{ \bigg/ }} \newcommand{\openimmerse}{\underset{\scriptscriptstyle O}{\hookrightarrow}} \newcommand{\qtext}[1]{{\quad \operatorname{#1} \quad}} \newcommand{\roof}[3]{#1 {\, \scriptstyle {}^\swarrow\, } #2 {\, \scriptstyle {}^\searrow\,} #3} \newcommand{\shift}[2]{{ \Sigma^{\scriptstyle[#2]} #1 }} \newcommand{\squares}[1]{{ {#1}_{\scriptscriptstyle \square} }} \newcommand{\weakeq}{\underset{\scriptscriptstyle W}{\rightarrow}} \newcommand{\congas}[1]{\underset{#1}{\cong}} \newcommand{\congbecause}[1]{\overset{#1}{\cong}} \newcommand{\equalsbecause}[1]{\overset{#1}{=}} \newcommand{\pwiso}{\underset{\mathrm{pw}}{\cong}} \newcommand{\lshriek}{{}_{!}} \newcommand{\pushf}{{}^{*}} \newcommand{\cofinal}{\mathsf{\emptyset}} \newcommand{\final}{\theset{\pt}} \newcommand{\freezmod}[1]{\ZZ\left[ {#1} \right]} \newcommand{\conjugate}[1]{{\overline{{#1}}}} \newcommand{\closure}[1]{\overline{#1}} \newcommand{\univcover}[1]{\overline{#1}} \newcommand{\bar}[1]{\overline{#1}} \newcommand{\hat}[1]{\widehat{#1}} \newcommand{\bundle}[1]{\mathcal{#1}} \newcommand{\vector}[1]{\mathbf{#1}} \newcommand{\vhat}[1]{\widehat{ \vector{#1} }} \newcommand{\diagonal}[1]{\Delta} \newcommand{\Diagonal}[1]{\Delta} \newcommand{\correspond}[1]{\theset{\substack{#1}}} \newcommand{\converges}[1]{\overset{#1}} \newcommand{\convergesto}[1]{\overset{#1}\too} \newcommand{\ddd}[2]{{\frac{d #1}{d #2}\,}} \newcommand{\dd}[2]{{\frac{\partial #1}{\partial #2}\,}} \newcommand{\evalfrom}{\Big|} \newcommand{\restrictionof}[2]{{\left.{{#1}} \right|_{{#2}} }} \newcommand{\ddt}{\tfrac{\dif}{\dif t}} \newcommand{\ddx}{\tfrac{\dif}{\dif x}} \newcommand{\logd}{{ \del^{\scriptsize \log} }} \newcommand{\theset}[1]{\left\{{#1}\right\}} \newcommand{\thevector}[1]{{\left[ {#1} \right]}} \newcommand{\mltext}[1]{\left\{\begin{array}{c}#1\end{array}\right\}} \newcommand{\Suchthat}{\middle\vert} \newcommand{\multinomial}[1]{\left(\!\!{#1}\!\!\right)} \newcommand{\realpart}[1]{{\mathcal{Re}({#1})}} \newcommand{\sheaf}[1]{\operatorname{\mathcal{#1}}} \newcommand{\smpt}[1]{\setminus\theset{#1}} \newcommand{\smts}[1]{\setminus\theset{ #1 }} \newcommand{\stirlingfirst}[2]{\genfrac{[}{]}{0pt}{}{#1}{#2}} \newcommand{\stirling}[2]{\genfrac\{\}{0pt}{}{#1}{#2}} \newcommand{\thecat}[1]{\mathbf{#1}} \newcommand{\constantsheaf}[1]{\underline{#1}} \newcommand{\vecc}[2]{\textcolor{#1}{\textbf{#2}}} \newcommand{\places}[1]{\mathrm{Pl}\qty{#1}} \newcommand{\ZZlocal}[1]{{ \ZZ_{\hat{#1}} }} \newcommand{\rad}[1]{\sqrt{#1}} \newcommand{\elts}[2]{{ {#1}_1, {#1}_2, \cdots, {#1}_{#2}}} \newcommand{\tselts}[2]{{ \theset{ {#1}_1, {#1}_2, \cdots, {#1}_{#2} } }} \newcommand{\mix}[1]{\overset{\scriptscriptstyle {#1} }{\times}} \newcommand{\fiberproduct}[1]{\underset{\scriptscriptstyle {#1} }{\times}} \newcommand{\fiberprod}[3]{{#1} \fiberproduct{#2} {#3}} \newcommand{\basechange}[1]{{ \fiberproduct{k} {#1} }} \newcommand{\fprod}[3]{\fiberprod{#1}{#2}{#3}} \newcommand{\qsymb}[2]{{ \left( {#1} \over {#2} \right) }} \newcommand{\kx}[1]{k[x_1, \cdots, x_{#1}]} \newcommand{\lktt}[1]{{L_{\mathrm{K3}, #1}}} \newcommand{\fractionalpart}[1]{\theset{#1}} \newcommand{\integerpart}[1]{\left[ {#1}\right]} \newcommand{\zadjoin}[1]{\ZZ\left[ {#1} \right]} \newcommand{\mapscorrespond}[2]{\mathrel{\operatorname*{\rightleftharpoons}_{#2}^{#1}}} \newcommand{\mapsvia}[1]{\xrightarrow{#1}} \newcommand{\mapsfromvia}[1]{\xleftarrow{#1}} \newcommand{\mapstovia}[1]{\xmapsto{#1}} \newcommand{\birationaliso}{\overset{\sim}{\rationalmap}} \newcommand{\sbirational}{\overset{\sim_{ \Stab} }{\rationalmap}} \newcommand{\isovia}[1]{\underset{#1}{\iso}} \newcommand{\isoin}[1]{\overset{#1}{\iso}} \newcommand{\injectsvia}[1]{\xhookrightarrow{#1}} \newcommand{\injectsfromvia}[1]{\xhookleftarrow{#1}} \newcommand{\relspec}{\underline{ \operatorname{Spec}}} \newcommand{\nerve}[1]{{ \mathcal{N}({#1}) }} \newcommand{\realize}[1]{{ \abs{#1} }} \newcommand{\opcat}[1]{{ {#1}^{\operatorname{op}} }} \newcommand{\oppositeof}[1]{{ {#1}^{\mathrm{op}} }} \newcommand{\dualof}[1]{{ {#1}^{\vee} }} \newcommand{\doubledualof}[1]{{ {#1}^{\vee\vee} }} \newcommand{\inverseof}[1]{{ {#1}^{-1} }} \newcommand{\unitsof}[1]{{ {#1}^{\times} }} \newcommand{\nonzeroof}[1]{{ {#1}^{\bullet} }} \newcommand{\interiorof}[1]{{ {#1}^{\circ} }} \newcommand{\sepclosure}[1]{{ {#1}^{\operatorname{sep}} }} \newcommand{\tiltof}[1]{{ {#1}^{\flat} }} \newcommand{\plusconstruction}[1]{{ {#1}^{+} }} \newcommand{\completionat}[2]{{ {#1}^{\wedge}_{#2} }} \newcommand{\procompletion}[1]{{ {#1}^{\wedge_{\scriptscriptstyle \pro}} }} \newcommand{\isoclasses}[1]{{ {#1}_{/\sim} }} \newcommand{\glue}[1]{{ \Disjoint_{#1} }} \newcommand{\normcomplex}[1]{{\norm{\complex{#1}}}} \newcommand{\Extalgebra}{\cocomplex{\bigwedge}} \newcommand{\Extalg}{\Extalgebra} \newcommand{\Extcomplex}{\cocomplex{ \Extalgebra}} \newcommand{\drcomplex}{{\cocomplex{\Omega}}} \newcommand{\cxH}{{\complex{H}}} \newcommand{\ccxH}{{\cocomplex{H}}} \newcommand{\sheafhom}{\mathop{\mathcal{H}\! \mathit{om}}} \newcommand{\smallprod}{{ \scriptscriptstyle\prod }} \newcommand{\eqLH}{{ \equalsbecause{\scriptscriptstyle\text{LH}} }} \newcommand{\eqae}{\underset{\ae}{=}} \newcommand{\eq}{\operatorname*{=}} \newcommand{\RM}[1]{\textup{\uppercase\expandafter{\romannumeral#1}}%} \newcommand{\caniso}{{ \underset{\can}{\iso} }} \newcommand{\dif}{\mathop{}\!\operatorname{d}} \newcommand{\rotate}[2]{{\style{display: inline-block; transform: rotate(#1deg)}{#2}}} \newcommand{\rrrarrows}{\mathrel{\substack{\textstyle\rightarrow\\[-0.6ex] \textstyle\rightarrow \\[-0.6ex] \textstyle\rightarrow}}} \newcommand{\righttriplearrows}{\operatorname{{\; \tikz{ \foreach \y in {0, 0.1, 0.2} { \draw [-stealth] (0, \y) -- +(0.5, 0);}} \; }}} \newcommand{\bdlattice}[2]{\overline{#1}_{ #2 }} \newcommand{\orthcomp}[2]{#1^{\perp #2}} \newcommand{\thecone}[1]{\mathfrak{#1}} \newcommand{\theposet}[1]{\mathcal{#1}} \newcommand{\modulistack}[1]{\mathcal{#1}} \newcommand{\RN}[1]{\textup{\uppercase\expandafter{\romannumeral#1}}} \newcommand{\torcptf}[2]{\overline{#1}^{#2}} \newcommand{\Sets}{{\mathsf{Set}}} \newcommand{\Poset}{\mathsf{Poset}} \newcommand{\Groups}{{\mathsf{Group}}} \newcommand{\Grp}{{\mathsf{Grp}}} \newcommand{\Ar}{{\mathsf{Ar}}} \newcommand{\Mot}{{\mathsf{Mot}}} \newcommand{\SW}{{\mathsf{SW}}} \newcommand{\cof}{{\mathsf{cof}}} \newcommand{\fib}{{\mathsf{fib}}} \newcommand{\der}{{\mathsf{d}}} \newcommand{\dg}{{\mathsf{dg}}} \newcommand{\comm}{{\mathsf{C}}} \newcommand{\pre}{{\mathsf{pre}}} \newcommand{\fn}{{\mathsf{fn}}} \newcommand{\smooth}{{\mathsf{sm}}} \newcommand{\Aff}{{\mathsf{Aff}}} \newcommand{\Ab}{{\mathsf{Ab}}} \newcommand{\Add}{{\mathsf{Add}}} \newcommand{\Assoc}{\mathsf{Assoc}} \newcommand{\Ch}{\mathsf{Ch}} \newcommand{\Coh}{{\mathsf{Coh}}} \newcommand{\Comm}{\mathsf{Comm}} \newcommand{\Corr}{\mathsf{Cor}} \newcommand{\Fin}{{\mathsf{Fin}}} \newcommand{\Free}{\mathsf{Free}} \newcommand{\Tors}{\mathsf{Tors}} \newcommand{\Perf}{\mathsf{Perf}} \newcommand{\Unital}{\mathsf{Unital}} \newcommand{\eff}{\mathsf{eff}} \newcommand{\Dc}{\mathbf{D}} \newcommand{\Db}{\mathsf{D}^b} \newcommand{\db}{\Db} \newcommand{\Const}{\mathsf{Const}} \newcommand{\Stable}{\mathsf{Stab}} \newcommand{\Vect}{{ \mathsf{Vect}}} \newcommand{\kvect}{{ \mathsf{Vect}\slice{k}}} \newcommand{\loc}{{\mathsf{loc}}} \newcommand{\locfree}{{\mathsf{locfree}}} \newcommand{\Bun}{{\mathsf{Bun}}} \newcommand{\Prinbun}{{ \mathsf{PrinBun}}} \newcommand{\bung}{{\mathsf{Bun}_G}} \newcommand{\Local}{\mathsf{Local}} \newcommand{\Field}{\mathsf{Field}} \newcommand{\Number}{\mathsf{Number}} \newcommand{\Numberfield}{\Field\slice{\QQ}} \newcommand{\NF}{\Numberfield} \newcommand{\Art}{\mathsf{Art}} \newcommand{\Global}{\mathsf{Global}} \newcommand{\Ring}{\mathsf{Ring}} \newcommand{\CMon}{\mathsf{CMon}} \newcommand{\CRing}{\mathsf{CRing}} \newcommand{\DedekindDomain}{\mathsf{DedekindDom}} \newcommand{\IntDomain}{\mathsf{IntDom}} \newcommand{\Dom}{\mathsf{Dom}} \newcommand{\Domain}{\mathsf{Domain}} \newcommand{\DVR}{\mathsf{DVR}} \newcommand{\Dedekind}{\mathsf{Dedekind}} \newcommand{\Quat}{{\mathsf{Quat}}} \newcommand{\Mod}{{\mathsf{Mod}}} \newcommand{\modr}{\modsright{R}} \newcommand{\grMod}{{\mathsf{grMod}}} \newcommand{\zmod}{\modsleft{\ZZ}} \newcommand{\qmod}{\modsleft{\QQ}} \newcommand{\rmod}{\modsleft{R}} \newcommand{\kmod}{\modsleft{k}} \newcommand{\cmod}{\modsleft{ \CC }} \newcommand{\fmod}{\modsleft{ \FF }} \newcommand{\oxmods}{\mods{\OO_X}} \newcommand{\amod}{\mods{A}} \newcommand{\gmod}{\mods{G}} \newcommand{\lmod}{\mods{L}} \newcommand{\Dmod}{\modsleft{\mathcal{D}}} \newcommand{\dmod}{\Dmod} \newcommand{\gr}{{\mathsf{gr}\,}} \newcommand{\mmod}{{\dash\mathsf{Mod}}} \newcommand{\Rep}{{\mathsf{Rep}}} \newcommand{\Irr}{{\mathsf{Irr}}} \newcommand{\Adm}{{\mathsf{Adm}}} \newcommand{\semisimp}{{\mathsf{ss}}} \newcommand{\Hodge}{{\mathsf{Hodge}}} \newcommand{\VectBundle}{{ \Bun\qty{\GL_r}}} \newcommand{\VectSp}{{ \VectSp }} \newcommand{\VectBun}{{ \VectBundle }} \newcommand{\Bung}{{ \Bun\qty{G}}} \newcommand{\Alg}{\mathsf{Alg}} \newcommand{\Hopf}{\mathsf{Hopf}} \newcommand{\alg}{\Alg} \newcommand{\scalg}{\mathsf{sCAlg}} \newcommand{\cAlg}{{\mathsf{cAlg}}} \newcommand{\calg}{\mathsf{CAlg}} \newcommand{\liegmod}{{\mathfrak{g}\dash\mathsf{Mod}}} \newcommand{\liealg}{{\mathsf{Lie}\dash\Alg}} \newcommand{\Lie}{\mathsf{Lie}} \newcommand{\kalg}{{}_{k} \Alg} \newcommand{\kAlg}{\kalg} \newcommand{\falg}{{}_{\FF} \Alg} \newcommand{\ralg}{{}_{R} \Alg} \newcommand{\rAlg}{\ralg} \newcommand{\zalg}{{}_{\ZZ} \Alg} \newcommand{\CCalg}{{}_{\CC} \Alg} \newcommand{\dga}{{\mathsf{dg\Alg}}} \newcommand{\cdga}{{ \mathsf{c}\dga }} \newcommand{\FMP}{\mathsf{FMP}} \newcommand{\dgla}{\dg\Lie\Alg} \newcommand{\DGLA}{\dgla} \newcommand{\Poly}{{\mathsf{Poly}}} \newcommand{\Hk}{{\mathsf{Hk}}} \newcommand{\Asm}{{\mathsf{Asm}}} \newcommand{\kSch}{{\mathsf{Sch}_{/k}}} \newcommand{\Grpd}{{\mathsf{Grpd}}} \newcommand{\inftyGrpd}{{ \underset{\infty}{ \Grpd }}} \newcommand{\Algebroid}{{\mathsf{Algd}}} \newcommand{\Loc}{\mathsf{Loc}} \newcommand{\Locsys}{\mathsf{LocSys}} \newcommand{\RingedSpace}{\mathsf{RingSp}} \newcommand{\LRS}{\Loc\RingedSpace} \newcommand{\IndCoh}{{\mathsf{IndCoh}}} \newcommand{\dbcoh}{\mathsf{D}^b\mathsf{Coh}} \newcommand{\DbCoh}{\dbcoh} \newcommand{\DCoh}{\mathsf{D}\mathsf{Coh}} \newcommand{\dcoh}{\DCoh} \newcommand{\QCoh}{{\mathsf{QCoh}}} \newcommand{\qcoh}{\QCoh} \newcommand{\ind}{\Indcat} \newcommand{\Pro}{\mathsf{pro}} \newcommand{\pro}{\Pro} \newcommand{\Cov}{{\mathsf{Cov}}} \newcommand{\presh}{\underset{ \mathsf{pre}} {\mathsf{Sh}}} \newcommand{\prest}{{\underset{ \mathsf{pre}} {\mathsf{St}} }} \newcommand{\Descent}{{\mathsf{Descent}}} \newcommand{\Desc}{{\mathsf{Desc}}} \newcommand{\FFlat}{{\mathsf{FFlat}}} \newcommand{\Perv}{\mathsf{Perv}} \newcommand{\smsch}{{ \smooth\Sch }} \newcommand{\Sch}{{\mathsf{Sch}}} \newcommand{\Schf}{{\mathsf{Schf}}} \newcommand{\Sh}{{\mathsf{Sh}}} \newcommand{\Stacks}{{\mathsf{St}}} \newcommand{\Var}{{\mathsf{Var}}} \newcommand{\Vark}{{ \Var_{/k}}} \newcommand{\Open}{{\mathsf{Open}}} \newcommand{\CW}{{\mathsf{CW}}} \newcommand{\ssets}{\mathsf{sSet}} \newcommand{\hoTop}{{\mathsf{hoTop}}} \newcommand{\hoType}{{\mathsf{hoType}}} \newcommand{\ho}{{\mathsf{ho}}} \newcommand{\SHC}{{\mathsf{SHC}}} \newcommand{\SH}{{\mathsf{SH}}} \newcommand{\Spaces}{{\mathsf{Spaces}}} \newcommand{\Spectra}{{\mathsf{Sp}}} \newcommand{\Sp}{{\mathsf{Sp}}} \newcommand{\Top}{{\mathsf{Top}}} \newcommand{\Bord}{{\mathsf{Bord}}} \newcommand{\TQFT}{{\mathsf{TQFT}}} \newcommand{\Kc}{{\mathsf{K^c}}} \newcommand{\triang}{{\mathsf{triang}}} \newcommand{\TTC}{{\mathsf{TTC}}} \newcommand{\dchrmod}{{\derivedcat{\Ch(\rmod)}}} \newcommand{\Finset}{{\mathsf{FinSet}}} \newcommand{\Cat}{\mathsf{Cat}} \newcommand{\Fun}{{\mathsf{Fun}}} \newcommand{\Kan}{{\mathsf{Kan}}} \newcommand{\Monoid}{\mathsf{Mon}} \newcommand{\Arrow}{\mathsf{Arrow}} \newcommand{\quasiCat}{{ \mathsf{quasiCat}}} \newcommand{\inftycat}{{ \underset{\infty}{ \Cat} }} \newcommand{\core}{{ \mathsf{core}}} \newcommand{\Indcat}{\mathsf{Ind}} \newcommand{\Prism}{\mathsf{Prism}} \newcommand{\Solid}{\mathsf{Solid}} \newcommand{\WCart}{\mathsf{WCart}} \newcommand{\Quadform}{{\mathsf{QuadForm}}} \newcommand{\HI}{{\mathsf{HI}}} \newcommand{\DM}{{\mathsf{DM}}} \newcommand{\hoA}{{\mathsf{ho}_*^{\scriptstyle \AA^1}}} \newcommand{\Tw}{\mathsf{Tw}} \newcommand{\SB}{\mathsf{SB}} \newcommand{\CSA}{\mathsf{CSA}} \newcommand{\CSS}{{ \mathsf{CSS}}} \newcommand{\FGL}{\mathsf{FGL}} \newcommand{\FI}{{\mathsf{FI}}} \newcommand{\CE}{{\mathsf{CE}}} \newcommand{\Fuk}{{\mathsf{Fuk}}} \newcommand{\Lag}{{\mathsf{Lag}}} \newcommand{\Mfd}{{\mathsf{Mfd}}} \newcommand{\Riem}{\mathsf{Riem}} \newcommand{\Wein}{{\mathsf{Wein}}} \newcommand{\deltaring}{{\delta\dash\mathsf{Ring}}} \newcommand{\terminal}{{ 0_{\scriptscriptstyle \uparrow}}} \newcommand{\initial}{{ \mathscr \emptyset^{\scriptscriptstyle \downarrow}}} \newcommand{\coeq}{\operatorname{coeq}} \newcommand{\cocoeq}{\operatorname{eq}} \newcommand{\cat}[1]{\mathsf{#1}} \newcommand{\GSets}{{G\dash\mathsf{Set}}} \newcommand{\derivedcat}[1]{\Dc {#1}} \newcommand{\bderivedcat}[1]{\Db {#1}} \newcommand{\ChainCx}[1]{\mathsf{Ch}\qty{ #1 }} \newcommand{\Fieldsover}[1]{{ \mathsf{Fields}_{#1}}} \newcommand{\torsors}[1]{{\mathsf{#1}\dash\mathsf{Torsors}}} \newcommand{\torsorsright}[1]{\mathsf{Torsors}\dash\mathsf{#1}} \newcommand{\torsorsleft}[1]{\mathsf{#1}\dash\mathsf{Torsors}} \newcommand{\bimods}[2]{({#1}, {#2})\dash\mathsf{biMod}} \newcommand{\modsleft}[1]{{}_{#1}\Mod} \newcommand{\modsright}[1]{\Mod_{#1}} \newcommand{\mods}[1]{\modsleft{#1}} \newcommand{\stmods}[1]{{\mathsf{#1}\dash\mathsf{stMod}}} \newcommand{\grmods}[1]{{\mathsf{#1}\dash\mathsf{grMod}}} \newcommand{\comods}[1]{{\mathsf{#1}\dash\mathsf{coMod}}} \newcommand{\gsetsleft}[1]{{}_{#1}\Sets} \newcommand{\gsetsright}[1]{\Sets_{#1}} \newcommand{\gset}[1]{\gsetsleft{#1}} \newcommand{\gsets}[1]{\gset{#1}} \newcommand{\VectBundlerk}[1]{{ \Bun\qty{\GL_{#1}}}} \newcommand{\VectBunrk}[1]{{ \VectBundlerk{#1}}} \newcommand{\algs}[1]{{ {}_{#1} \Alg }} \newcommand{\inftycatn}[1]{{ \underset{(\infty, {#1})}{ \Cat} }} \newcommand{\GSpaces}{{G\dash\mathsf{Spaces}}} \newcommand{\gspaces}[1]{{#1}\dash{\mathsf{Spaces}}} \newcommand{\Torsor}[1]{{\mathsf{#1}\dash\mathsf{Torsor}}} \newcommand{\Torsorleft}[1]{{\mathsf{#1}\dash\mathsf{Torsor}}} \newcommand{\Torsorright}[1]{{\mathsf{Torsor}\dash\mathsf{#1}}} \newcommand{\adj}[4]{#1 \mathrel{\underset{#4}{\overset{#3}{\rightleftarrows}}} #2} \newcommand{\tmf}{\mathrm{tmf}} \newcommand{\taf}{\mathrm{taf}} \newcommand{\TAF}{\mathrm{TAF}} \newcommand{\TMF}{\mathrm{TMF}} \newcommand{\String}{\mathrm{String}} \newcommand{\BO}{{\B \Orth}} \newcommand{\EO}{{\mathsf{E} \Orth}} \newcommand{\BSO}{{\B\SO}} \newcommand{\ESO}{{\mathsf{E}\SO}} \newcommand{\BG}{{\B G}} \newcommand{\EG}{{\mathsf{E} G}} \newcommand{\BP}{{\operatorname{BP}}} \newcommand{\BU}{\B{\operatorname{U}}} \newcommand{\MO}{{\operatorname{MO}}} \newcommand{\MSO}{{\operatorname{MSO}}} \newcommand{\MSpin}{{\operatorname{MSpin}}} \newcommand{\MString}{{\operatorname{MString}}} \newcommand{\MU}{{\operatorname{MU}}} \newcommand{\KO}{{\operatorname{KO}}} \newcommand{\KU}{{\operatorname{KU}}} \newcommand{\ku}{{\operatorname{ku}}} \newcommand{\smashprod}{\wedge} \newcommand{\hofib}{{\operatorname{hofib}}} \newcommand{\cofib}{{\operatorname{cofib}}} \newcommand{\hocofib}{{\operatorname{hocofib}}} \newcommand{\Loop}{{\Omega}} \newcommand{\Loops}{\Loop} \newcommand{\Suspend}{{\Sigma}} \newcommand{\Suspendpinf}{\operatorname{{\Sigma_+^\infty}}} \newcommand{\Loopinf}{\operatorname{{\Omega^\infty}}} \newcommand{\Loopsinf}{\Loopinf} \)

41  Discriminant orbits of the Coble lattice

Remark 41.1 The Coble period lattice \(T_\Co = \generators{2}\oplus E_{10}(2)\) is the twist by \(2\) of an odd unimodular lattice, and this single fact controls both its isometry group and its discriminant form. We compute the discriminant quadratic form \((A_{T_\Co}, q_{T_\Co})\) explicitly, determine its isometry group and the decomposition of its isotropic classes into orbits, and record the bridge between that finite datum and the primitive isotropic vectors of \(T_\Co\) themselves. Throughout we use the discriminant apparatus of the discriminant-form definition (Definition 37.8) and the invariant triple \((r, a, \delta)\) of the Lattice Theory section.

41.1 The Coble lattice as a twist

Proposition 41.2 ($T_\Co$ is a twisted odd unimodular lattice) Set \[ B \definedas \generators{1}\oplus E_{10} = \generators{1}\oplus U\oplus E_8 . \] Then \(B\) is odd and unimodular of signature \((2,9)\), so \(B\cong\latI_{2,9}\), and \[ T_\Co = \generators{2}\oplus E_{10}(2) = B(2) \cong \latI_{2,9}(2) . \] Consequently \(\Orth(T_\Co) = \Orth(B)\) as subgroups of \(\GL(B)\), and a vector of \(T_\Co\) is isotropic, respectively primitive, exactly when it is isotropic, respectively primitive, as a vector of \(B\).

Proof. The lattice \(E_{10} = U\oplus E_8\) is even and unimodular of signature \((1,9)\) (the Enriques-lattice definition (Definition 39.6)), so \(B = \generators{1}\oplus E_{10}\) is unimodular of signature \((2,9)\) and is odd because the generator of \(\generators{1}\) has norm \(1\). By the classification of indefinite unimodular lattices (the indefinite unimodular classification (Theorem 38.20)) an odd unimodular lattice of signature \((2,9)\) is isometric to \(\latI_{2,9}\). Twisting distributes over orthogonal direct sums and \(\generators{1}(2) = \generators{2}\), whence \(B(2) = \generators{2}\oplus E_{10}(2) = T_\Co\).

A twist leaves the underlying \(\ZZ\)-module unchanged and multiplies the form by a nonzero scalar, so an automorphism of the module preserves \(\beta_B\) if and only if it preserves \(2\beta_B = \beta_{B(2)}\); this gives \(\Orth(T_\Co) = \Orth(B)\). The same scaling shows \(\beta_{T_\Co}(v,v) = 2\beta_B(v,v)\) vanishes exactly when \(\beta_B(v,v)\) does, and primitivity is a property of the module alone.

Remark 41.3 The presentation \(T_\Co\cong\latI_{2,9}(2)\) is the one recorded in the K3-cover invariants remark (Remark 32.1), and it is the form in which the divisibility computation of the divisibility lemma (Lemma 63.2) is carried out. Applying the indefinite unimodular classification (Theorem 38.20) once more to \(U\oplus U\oplus\latI_{0,7}\), which is odd unimodular of signature \((2,9)\), gives the further presentation \[ T_\Co \cong U(2)^{\oplus 2}\oplus\generators{-2}^{\oplus 7} = U(2)^{\oplus 2}\oplus A_1^{\oplus 7} , \] in which the Witt index \(2\) and the negative-definite rank-\(7\) complement of a maximal isotropic subspace are visible in the presentation itself.

Proposition 41.4 ($T_\Co$ is the twist of a split maximal lattice) The lattice \(B\cong\latI_{2,9}\) of the twist proposition (Proposition 41.2) is maximal in the sense of the maximal-lattice definition (Definition 38.15) and split in the sense of the split-maximal definition (Definition 38.17): \[ B \cong U\oplus U\oplus\latI_{0,7} . \] In a decomposition \(T_\Co = B(2)\) with \(B = U\oplus U\oplus\latI_{0,7}\), an isotropic generator \(e\) of one hyperbolic summand and the plane \(J\) spanned by isotropic generators of both have \[ e^{\perp}/e \cong \latI_{1,8}(2) = (9,9,1)_1, \qquad J^{\perp}/J \cong \latI_{0,7}(2) \cong A_1^{\oplus 7} = (7,7,1)_0 . \]

Proof. \(B\) is unimodular, hence maximal by the maximal-overlattice lemma (Lemma 38.16). The lattice \(U\oplus U\oplus\latI_{0,7}\) is unimodular of signature \((2,9)\) and odd, because \(\latI_{0,7}\) is, so it is isometric to \(\latI_{2,9}\cong B\) by the indefinite unimodular classification (Theorem 38.20); this exhibits \(B\) in the shape required by the split-maximal definition (Definition 38.17), as the maximal-splitting theorem (Theorem 38.18) also predicts for \(n = 9\geq 5\). For the quotients, take \(e\) to be an isotropic generator of the first hyperbolic summand of \(B\cong U\oplus U\oplus\latI_{0,7}\); then \(e^{\perp B} = \ZZ e\oplus U\oplus\latI_{0,7}\) and \(e^{\perp}/e\cong U\oplus\latI_{0,7}\cong\latI_{1,8}\), which is odd unimodular of signature \((1,8)\). Taking \(J\) to be spanned by isotropic generators of the two hyperbolic summands gives \(J^{\perp B} = J\oplus\latI_{0,7}\) and \(J^{\perp}/J\cong\latI_{0,7}\). Twisting by \(2\) and reading off invariants gives \(\latI_{1,8}(2) = (9,9,1)\) of signature \((1,8)\) and \(\latI_{0,7}(2) = \generators{-2}^{\oplus 7} = (7,7,1)\) of signature \((0,7)\).

Remark 41.5 Since \(\Orth^+(T_\Co) = \Orth^+(B)\) and both isotropy and primitivity are unchanged by the twist, the split-maximal proposition (Proposition 41.4) places \(T_\Co\) under the split-maximal isotropic transitivity theorem (Theorem 38.19): this is the mechanism behind the unpolarized-cusp theorem (Theorem 85.27), and the computation above identifies the two boundary lattices there with the Coble cusp invariants \((9,9,1)_1\) and \((7,7,1)_0\) used in the cusp correspondence. The \(1\)-cusp lattice \(\latI_{0,7}(2)\cong A_1^{\oplus 7}\) is negative definite of rank \(7\), consistent with Witt index \(2\) in signature \((2,9)\): \(11 - 2\cdot 2 = 7\).

41.2 The discriminant form of a twisted unimodular lattice

Proposition 41.6 (Discriminant form of $M(2)$ for $M$ unimodular) Let \(M\) be a unimodular lattice of rank \(r\) and let \(L\definedas M(2)\). Then \[ \dualof{L} = \tfrac{1}{2}M, \qquad A_L = \tfrac{1}{2}M/M \cong M/2M \cong (\ZZ/2\ZZ)^r , \] so \(L\) is \(2\)-elementary with \(a = r\), and the discriminant quadratic form is \[ q_L\!\left(\tfrac{1}{2}x + L\right) = \tfrac{1}{2}\,\beta_M(x, x) \bmod 2\ZZ, \qquad x\in M . \] In particular the class of \(\tfrac{1}{2}x\) is isotropic for \(q_L\) if and only if \[ \beta_M(x, x)\equiv 0 \pmod 4 . \]

Proof. Under the geometric identification of the dual lattice (the geometric dual-lattice identification (Theorem 37.13)), \(\dualof{L}\) is the set of \(v\in M_\QQ\) with \(2\beta_M(v, M)\iscontainedin\ZZ\), that is \(\beta_M(v, M)\iscontainedin\tfrac12\ZZ\). Since \(M\) is unimodular the map \(M\to \dualof{M}\) is an isomorphism, so this set is exactly \(\tfrac12 M\). The quotient \(\tfrac12 M/M\) is carried isomorphically to \(M/2M\) by multiplication by \(2\), giving \(A_L\cong(\ZZ/2\ZZ)^r\) and \(a = r\). For the form, \(\beta_L = 2\beta_M\) gives \[ q_L\!\left(\tfrac12 x + L\right) = \beta_L\!\left(\tfrac12 x, \tfrac12 x\right) = 2\cdot\tfrac14\beta_M(x, x) = \tfrac12\beta_M(x, x) \bmod 2\ZZ , \] and this vanishes in \(\QQ/2\ZZ\) precisely when \(\beta_M(x,x)\in 4\ZZ\).

Definition 41.7 (The mod-$4$ norm on $B/2B$) For \(B = \generators{1}\oplus E_{10}\) as in the twist proposition (Proposition 41.2), define \[ \begin{aligned} Q: B/2B &\to \ZZ/4\ZZ \\ x + 2B &\mapsto \beta_B(x, x) \bmod 4 . \end{aligned} \] This is well defined, since \(\beta_B(x + 2z, x + 2z) = \beta_B(x,x) + 4\beta_B(x,z) + 4\beta_B(z,z)\). Under the identification \(A_{T_\Co}\cong B/2B\) of the twisted-unimodular discriminant proposition (Proposition 41.6) one has \(q_{T_\Co} = \tfrac12 Q\), so \(Q\) and \(q_{T_\Co}\) have the same fibers and \(\Orth(A_{T_\Co}, q_{T_\Co})\) is the stabilizer in \(\GL(B/2B)\) of the four fibers of \(Q\).

Proposition 41.8 (The fibers of $Q$) The four fibers of \(Q\) on the \(2^{11} = 2048\) classes of \(B/2B\) have cardinalities \[ \abs{\inverseof{Q}(0)} = 528,\quad \abs{\inverseof{Q}(1)} = 528,\quad \abs{\inverseof{Q}(2)} = 496,\quad \abs{\inverseof{Q}(3)} = 496 . \] In particular \(A_{T_\Co}\) contains exactly \(528\) isotropic classes, of which \(527\) are nonzero.

Proof. Write \(B = \generators{v}\oplus E_{10}\) with \(v^2 = 1\) and let \(x = \varepsilon v + y\) represent a class of \(B/2B\), with \(\varepsilon\in\theset{0,1}\) and \(y\) ranging over \(E_{10}/2E_{10}\). Then \(\beta_B(x,x) = \varepsilon + \beta_{E_{10}}(y,y)\), and since \(E_{10}\) is even the value \(\beta_{E_{10}}(y,y)\) is \(\equiv 0\) or \(2 \pmod 4\). Hence \(Q\) takes the value \(0\) or \(2\) on the classes with \(\varepsilon = 0\) and the value \(1\) or \(3\) on those with \(\varepsilon = 1\), and in both cases the split is governed by the single count \[ N_0 \definedas \#\theset{ y\in E_{10}/2E_{10} \mid \beta_{E_{10}}(y,y)\equiv 0 \pmod 4 } . \] The four fibers then have sizes \(N_0,\ N_0,\ 2^{10} - N_0,\ 2^{10} - N_0\) in the order listed.

To compute \(N_0\), observe that \(\bar q(y)\definedas\tfrac12\beta_{E_{10}}(y,y)\bmod 2\) is a quadratic form \(E_{10}/2E_{10}\to\bF_2\) whose polar form is the reduction of \(\beta_{E_{10}}\) modulo \(2\); the latter is nondegenerate because \(E_{10}\) is unimodular. Thus \(\bar q\) is a nondegenerate quadratic form on a \(10\)-dimensional \(\bF_2\)-vector space, and \(N_0 = \#\inverseof{\bar q}(0)\). The decomposition \(E_{10} = U\oplus E_8\) splits \(\bar q\) orthogonally. On \(U/2U\) the form is \(\bar q(ae + bf) = ab\), which is the hyperbolic plane over \(\bF_2\) and has \(3\) zeros; on \(E_8/2E_8\) the form is the reduction of the \(E_8\) form and has \(136\) zeros. Both are of plus type, hence so is their sum, and a nondegenerate plus-type form in dimension \(2n\) over \(\bF_2\) has \(2^{2n-1} + 2^{n-1}\) zeros. With \(n = 5\) this gives \[ N_0 = 2^{9} + 2^{4} = 512 + 16 = 528 , \] in agreement with the two summand counts \(3\cdot 136 + 1\cdot 120 = 528\). The remaining fiber sizes are \(2^{10} - 528 = 496\).

Remark 41.9 The counts \(\#A_{E_{10}(2)} = 1024\), \(\#I^0 = 528\) and \(\#I^1 = 496\) tabulated in the reference tables are exactly the numbers \(2^{10}\), \(N_0\) and \(2^{10} - N_0\) appearing in this proof, and the summand counts \(\#I^0(U(2)) = 3\), \(\#I^0(E_8(2)) = 136\) are the two zero-counts used to identify the type. The isotropic classes of \(A_{T_\Co}\) and of \(A_{E_{10}(2)}\) therefore coincide as sets: a class \(\varepsilon\bar v + \bar y\) is isotropic only if \(\varepsilon = 0\), because \(q_{T_\Co}(\bar v) = \tfrac12\notin\ZZ\) while \(q_{E_{10}(2)}\) is \(\ZZ\)-valued. This is the invariant \(\delta = 1\) of \(T_\Co\) read off from a distinguished class.

41.3 The isometry group of the discriminant form

Proposition 41.10 ($\Orth(q_{T_\Co})$ is the discriminant group of $E_{10}(2)$) Restriction to the subgroup \[ A^0 \definedas \theset{ x\in A_{T_\Co} \mid q_{T_\Co}(x)\in\ZZ/2\ZZ } \cong A_{E_{10}(2)} \] of index \(2\) induces an isomorphism \[ \Orth(A_{T_\Co}, q_{T_\Co}) \iso \Orth(A_{E_{10}(2)}, q_{E_{10}(2)}) , \] and hence \[ \abs{\Orth(A_{T_\Co}, q_{T_\Co})} = 2^{21}\cdot 3^5\cdot 5^2\cdot 7\cdot 17\cdot 31 = 46\,998\,591\,897\,600 . \]

Proof. Write \(A_{T_\Co} = \ZZ\bar h\oplus A_{E_{10}(2)}\) with \(\bar h\) the class of \(\tfrac12 h\) for \(h\) the generator of \(\generators{2}\), so that \(q_{T_\Co}(\bar h) = \tfrac12\) and \(\bar h\) is orthogonal to \(A_{E_{10}(2)}\) for the discriminant bilinear form. Since \(q_{E_{10}(2)}\) is \(\ZZ\)-valued, \(A^0 = A_{E_{10}(2)}\), and \(A^0\) is intrinsically defined by \(q_{T_\Co}\), hence preserved by every isometry. Restriction therefore gives a homomorphism \(\rho\colon\Orth(A_{T_\Co}, q_{T_\Co})\to\Orth(A^0, q_{T_\Co}|_{A^0})\).

\(\rho\) is injective. If \(g\) restricts to the identity on \(A^0\) then \(g(\bar h) = \bar h + z\) for some \(z\in A^0\), and preservation of the bilinear form gives \(b(z, y) = b(g\bar h, y) - b(\bar h, y) = 0\) for every \(y\in A^0\); the form \(q_{E_{10}(2)}\) is nondegenerate (the discriminant nondegeneracy proposition (Proposition 37.10)), so \(z = 0\).

\(\rho\) is surjective. Given \(g_0\in\Orth(A^0)\), extend it by \(\bar h\mapsto\bar h\); the extension preserves \(q_{T_\Co}\) because the decomposition \(A_{T_\Co} = \ZZ\bar h\perp A^0\) is orthogonal.

The order of \(\Orth(A_{E_{10}(2)}, q_{E_{10}(2)})\) is the one recorded in the reference tables.

Theorem 41.11 (Two orbits of isotropic classes) The group \(\Orth(A_{T_\Co}, q_{T_\Co})\) has exactly two orbits on the \(528\) isotropic classes of \(A_{T_\Co}\): the zero class, and the set of all \(527\) nonzero isotropic classes.

Proof. By the Coble discriminant-group proposition (Proposition 41.10) the action is that of \(\Orth(A_{E_{10}(2)}, q_{E_{10}(2)})\) on the singular vectors of the nondegenerate plus-type quadratic form \(\bar q\) on the \(10\)-dimensional \(\bF_2\)-space \(E_{10}/2E_{10}\) identified in the proof of the fiber-count proposition (Proposition 41.8). Witt’s extension theorem for nondegenerate quadratic forms over a field states that an isometry between subspaces extends to the whole space; applied to the lines spanned by two nonzero singular vectors it shows that the orthogonal group is transitive on nonzero singular vectors. The zero class is fixed, and by the fiber-count proposition (Proposition 41.8) there are \(528 - 1 = 527\) nonzero singular vectors.

41.4 From discriminant classes to lattice vectors

Proposition 41.12 (Primitive isotropic vectors and their discriminant classes) Every primitive isotropic \(v\in T_\Co\) has \(\div_{T_\Co}(v) = 2\), and its associated class \[ v^* \definedas \tfrac{1}{2}v + T_\Co \in A_{T_\Co} \] is a nonzero isotropic class. All such classes lie in the single nonzero orbit of the isotropic-class orbit theorem (Theorem 41.11).

Proof. The divisibility statement is the divisibility lemma (Lemma 63.2), and \(v^*\) has order \(\div_{T_\Co}(v) = 2\) in \(A_{T_\Co}\) (the discriminant-form definition (Definition 37.8) and the divisibility conventions of the Lattice Theory section), so \(v^*\neq 0\). Writing \(v\in B\) and using \(\beta_{T_\Co} = 2\beta_B\), isotropy of \(v\) gives \(\beta_B(v,v) = 0\), hence \(Q(v) = 0\) and \(q_{T_\Co}(v^*) = 0\) by the twisted-unimodular discriminant proposition (Proposition 41.6). The final assertion is the isotropic-class orbit theorem (Theorem 41.11), which has a single orbit of nonzero isotropic classes.

Remark 41.13 (What the finite orbit count does and does not determine) For the full orthogonal group the lattice-level statement is stronger than the finite one: \(\Orth^+(T_\Co)\) is transitive on primitive isotropic vectors and on primitive isotropic planes, with the quotients \(e^{\perp}/e\cong\latI_{1,8}(2)\) and \(J^{\perp}/J\cong\latI_{0,7}(2)\cong A_1^{\oplus 7}\) (the unpolarized-cusp theorem (Theorem 85.27)), and the primitive-isotropic-class proposition (Proposition 41.12) then places every primitive isotropic vector in the single nonzero orbit of the isotropic-class orbit theorem (Theorem 41.11).

For a subgroup \(\Gamma\leq\Orth(T_\Co)\) the passage runs the other way and is not automatic. The reduction map sends \(\Gamma\)-orbits of primitive isotropic vectors to \(\rho(\Gamma)\)-orbits of nonzero isotropic classes, but the integral parabolic stabilizer can have proper image in the finite stabilizer, so a finite orbit may split. The \(\gent\)-induced orbit decomposition of the \(528\) isotropic classes is computed in the Coble Heegner finite-orbit theorem (Theorem 42.9), and the lift of that finite decomposition to primitive isotropic vectors of \(T_\Co\) is open.

41.5 The Eichler criterion and its hypothesis

Remark 41.14 (Why the Eichler criterion is unavailable for $T_\Co$) The Eichler criterion (the Eichler criterion (Theorem 39.15)) reduces \(\widetilde{\SO}^+(L)\)-equivalence of primitive vectors to the pair \((v^2, v^*\bmod L)\), but only for lattices containing \(U^{\oplus 2}\). That hypothesis fails for \(T_\Co\): by the twist proposition (Proposition 41.2) every value of \(\beta_{T_\Co}\) is even, so no two vectors of \(T_\Co\) pair to \(1\) and \(T_\Co\) contains no copy of \(U\) at all, let alone two; the remark following the Eichler criterion (Theorem 39.15) records the same obstruction for \(S_\Co\) and \(\sen\). An orbit statement for \(T_\Co\) therefore needs a different mechanism. Two are available: the transitivity of the unpolarized-cusp theorem (Theorem 85.27) for the full orthogonal group, resting on the split-maximal proposition (Proposition 41.4), and the algorithms of (Dawes 2022) for a subgroup specified by its image in \(\Orth(q)\).