299 problems.
Qualifying Exam in Analysis, September 4, 2019, 9am–12noon (pp. 1–2)
- Convergence of positive continuous functions and Fatou-type inequality
- \(L^1\) convergence implies existence of a.e. convergent subsequence
- The convolution of two \(L^2(\mathbb R)\) functions is continuous
- Every closed convex subset of a Hilbert space has a unique element of minimal norm
- \(\int_0^\infty\frac{\log x}{x^2+2}\,dx\) by contour integration
- Polynomial growth of entire functions and derivatives of normal families
- A holomorphic function on the punctured disk dominated by a power of the logarithm
- Nonempty closed convex sets in a Hilbert space have unique minimum-norm points
ANALYSIS QUALIFYING EXAM: SPRING 2019 (p. 3)
- Weak convergence plus pointwise decay need not imply strong convergence in \(L^2(\mathbb R^d)\)
- Separate measurability and section functions of a measurable function of two variables
- Monotone convergence of continuous functions is uniform iff limit is continuous
- The sine integral converges, but \(\sin x/x\notin L^1(1,\infty)\)
- Automorphisms of the upper half plane
- Holomorphic off the real line and continuous everywhere implies entire
- Evaluating \(\int_0^\infty x^{-1/3}/(1+x)\,dx\)
- Punctured unit disk and annulus are not conformally equivalent
Johns Hopkins University, Department of Mathematics, Real and Complex analysis (undated, pp. 4–5)
- Dyadic averages of an \(L^1\) function converge almost everywhere
- Unit ball of \(L^2\) is not compact
- Banach space characterization via absolutely convergent series
- Entire functions with pointwise modulus bound are proportional
- Evaluating the sinc integral by contour integration
- Maximum modulus property forces holomorphic functions to be constant
- Bergman space is a Hilbert space
Johns Hopkins University, Department of Mathematics, Real and Complex analysis (undated, pp. 6–7)
- Dyadic averages of an \(L^1\) function converge almost everywhere
- Weak convergence plus norm convergence implies strong convergence in \(L^2\)
- Holder inequality, Young inequality, and \(L^p\) Banach spaces
- Entire function with zero coefficient at every center is polynomial
- Meromorphic function with pole has no holomorphic logarithm
- Holomorphic function in annulus approximable by polynomials extends to disc
- Bergman space embedding, normal family, and removable singularity
Qualifying Exam - Analysis-Fall 2017 (p. 8)
- Eventual equicontinuity at a continuity point of a monotone limit
- Continuity of translations in \(L^p(\mathbb R^n)\)
- Small sets for a Radon measure via the Vitali covering lemma
- The Schwarz lemma with a zero at an arbitrary point of the disk
- Entire functions with polynomially bounded real part are polynomials
- The two-circles bound for subharmonic functions
Qualifying Exam - Analysis - Spring 2017 (p. 9)
- Layer-cake formula with an absolutely continuous weight: \(\int_{\RR}\varphi\circ f\,dx=\int_0^\infty m(\{f>t\})\varphi'(t)\,dt\)
- Weak and strong convergence in Hilbert space, with Banach-Saks subsequence means
- Borel-Cantelli: measurable sets of summable measure
- Extremal second derivative among holomorphic maps into the unit disk
- Holomorphic functions on the punctured plane with a two-sided growth bound
- Unit modulus on the boundary circle forces the image to contain the disk
Qualifying Exam - Analysis - Fall 2016 (p. 10)
- \(L^2\) convergence has an almost-everywhere convergent subsequence
- Translates of a positive-measure set cover almost all of the line
- Norm-one sequences in an infinite-dimensional Hilbert space: subsequences
- Uniform limits on compact subsets of harmonic functions are harmonic
- A univalent branch of \(\sqrt{f(z^2)}\)
- Zero-count stability when the limit has no boundary zeros
QUALIFYING EXAM SPRING 2016 - ANALYSIS (p. 11)
- Absolute continuity of the Lebesgue integral
- Hardy-Littlewood maximal function bound via Vitali covering
- Layer-cake formula with a \(C^1\) weight on \([0,1]\)
- Bergman space is a Hilbert space
- Holomorphic self-map of disk with two fixed points is identity
- Entire function with unbounded zero set has essential singularity at infinity
- Zeros of \(2z^5-6z^2+z+1\) in a closed annulus
QUALIFYING EXAM - ANALYSIS - FALL 2015 (p. 12)
- A sequence converging to \(0\) in \(L^2\) has a subsequence converging almost everywhere
- Monotone and absolutely continuous functions: two true-or-false statements
- Products of orthonormal bases span the product \(L^2\) space
- Uniform approximation on the boundary preserves the zero count
- Entire functions with nonpositive real part are constant
- \(f^2\) and \(f^3\) holomorphic imply \(f\) holomorphic
- The logarithmic integral \(\int_0^\infty (\log x)^2/(1+x^2)\,dx\)
Qualifying Exam - Analysis - Spring 2015 (p. 13)
- A.e. convergence plus convergence of \(L^2\) norms implies \(L^2\) convergence
- Mollification does not increase the \(L^2\) norm
- An increasing convex function on \([0,1]\) is the integral of its derivative
- \(fg\in L^1\) for all \(g\in L^2\) implies \(f\in L^2\)
- Componentwise rigidity of a holomorphic conjugate product
- Nonconstant entire functions have dense image
- All zeros of \(z^5+3z^3+7\) lie in \(|z|<2\)
- Logarithmic bound on holomorphic function in annulus
Qualifying Exam - Analysis - Fall 2014 (p. 14)
- Convergence of \(L^1\) norms upgrades a.e. convergence to \(L^1\) convergence — Problem 1
- The Hardy-Littlewood maximal function is weak (1,1) — Problem 2
- Compact operators are norm limits of finite-rank operators — Problem 3
- Uniform convergence on the boundary gives uniform convergence on the region — Problem 4
- Evaluating \(\int_0^\infty\cos(ax)/(1+x^2)^2\,dx\) — Problem 5
- Entire functions bounded by a nonvanishing entire function are constant multiples — Problem 6
- Automorphisms of the unit disk are linear fractional transformations — Problem 7
QUALIFYING EXAM - ANALYSIS - SPRING 2014 (p. 15)
- Egoroff’s theorem for a dominated sequence, proved without invoking Egoroff — Problem 1
- Integral equals integral of distribution function — Problem 2
- Lipschitz condition equivalent to absolute continuity with bounded derivative — Problem 3
- Multiplication operator on \(L^2\) is self-adjoint but not compact — Problem 4
- Schwarz-Pick type inequality for holomorphic self-map of disk — Problem 5
- Fourier transform of the sinc function — Problem 6
- Zero derivative implies not one-to-one in any neighborhood — Problem 7
- An entire function of polynomial growth is a polynomial — Problem 8
QUALIFYING EXAM - ANALYSIS - FALL 2013 (p. 16)
- \(L^1\) integrability of integral transform — Problem 1
- Measurable set with dense complement and no isolated points — Problem 2
- Smooth compactly supported functions are dense in \(L^2\) — Problem 3
- Nonzero smooth compactly supported function with compactly supported Fourier transform — Problem 4
- \(\int_0^\infty\frac{\cos u}{u^4+1}\,du\) — Problem 5
- Distinct solutions of \(e^{z^2}=5z^5\) in the closed unit disk — Problem 6
- Entire functions bounded by \(|z|^2|\operatorname{Im}z|^2\) at infinity — Problem 7
Qualifying Exam - Analysis, May, 2013 (pp. 17–18)
- A continuous \(f\) with \(f^2\) holomorphic is holomorphic
- Zeros of \(z^4-6z+3\) in the unit disk and an annulus
- Growth bound on the disk from an upper bound on the real part
- Evaluating \(\int_0^\infty x^{1/2}/(4+x^2)\,dx\)
- Sum of two positive measure sets contains an interval
- Riemann-Lebesgue lemma and convolution identity
- \(\|f_n\|_2\to0\) implies an a.e.-convergent subsequence
- Weak convergence plus norm convergence implies strong convergence in \(L^2\)
ANALYSIS QUALIFYING EXAM, FALL 2012 (pp. 19–20)
- Zeros of a polynomial in the annulus from one to three
- Residue computation of the Fourier transform of \(\frac{1}{x^{2}+1}\)
- Maximal derivative of a disk self-map at an interior point
- Continuity across a segment plus holomorphy off it implies entire
- \(L^1\) convergence gives an a.e.-convergent subsequence but not uniform convergence
- Fatou’s lemma, the dominated convergence theorem, and a counterexample
- Convolutions of \(L^2\) functions and convolution operators on \(L^1\)
- \(L^\infty\) and weak-\(L^1\) bounds imply \(L^2\) boundedness
Analysis Qualifying Exam, May 9, 2012 (p. 21)
- Residue evaluation of \(\int_0^\infty (1+x^2)^{-2}\,dx\)
- Unique fixed point of a disk map whose boundary values lie in the open disk
- Removable singularity when real part is bounded below
- Half-plane preservation and two interpolation values force a translation
- Weak and strong convergence of squares in \(L^2\)
- Absolutely convergent series of \(L^1\) functions converges a.e. and in \(L^1\)
- Integral transform is absolutely continuous and vanishes at infinity
- Fourier transform is continuous and vanishes at infinity
ANALYSIS QUALIFYING EXAM, SEPTEMBER 2011 (pp. 22–23)
- \(\int_\gamma \frac{dz}{z^3\cos z}\) for \(|z-1|=2\)
- A harmonic function on the plane bounded below is constant
- Finite valence excludes an essential singularity
- Unique normalized rotations of a simply connected bounded domain
- An \(L^2\)-bounded sequence in \(L^2\) of the line without convergent subsequences
- Fourier-transform integrals over finite- and infinite-measure sets
- Small-level decay of the distribution function of an \(L^p\) function
- No convolution identity in \(L^1(\RR^n)\)
ANALYSIS QUALIFYING EXAM, MAY 2011 (pp. 24–25)
- Entire functions with unit modulus on the unit circle are monomials
- Weighted logarithmic derivative around two prescribed zeros
- A holomorphic self-map of a bounded domain has derivative at most one at a fixed point
- A logarithmic upper bound forces an entire harmonic function to be constant
- The running maximum of a bounded C1 sequence converges uniformly
- Absolutely summable Fourier coefficients give a continuous representative
- \(L^p\) norms converge to the \(L^\infty\) norm on a probability space
- Weak \(L^2\) convergence: lower semicontinuity and strong convergence from norm convergence
Analysis Qualifying Exam, Fall 2010 (pp. 26–27)
- \(L^2\) convergence with Gaussian weight
- Characteristic-function convolution and one-sided differentiation averages
- Schur’s test for integral operators
- Translation operator on \(L^2\) has no real eigenvalues
- Residues on a twice-traversed limaçon
- Vanishing first jets at the points \(1/n\)
- Entire functions dominated by \(|\operatorname{Re}z|^2+|z|^{3/2}\)
- The quadratic Schwarz bound for a two-sheeted branched disk map
ANALYSIS QUALIFYING EXAM, MAY 2010 (pp. 28–29)
- Removable singularity under the bound \(|f(z)|\le|z|^{-1/2}\)
- All integral values over simple closed curves avoiding two poles
- The Bergman space of the unit disk
- Harmonic conjugate on the exterior of the unit disk up to a logarithmic term
- Uniform \(H^\sigma\) bounds pass to an \(L^2\) limit
- Convolution with a compactly supported kernel maps \(L^p\) to \(L^q\) exactly when \(p\le q\)
- Differentiation under the integral sign with a dominated partial derivative
- Continuity of overlap measure and Steinhaus’ theorem
ANALYSIS QUALIFYING EXAM, SEPTEMBER 2009 (pp. 30–31)
- Pointwise versus uniform convergence of continuous functions
- Bilinear forms with polynomially weighted coefficients on l2
- Dyadic averages of an \(L^1\) function converge almost everywhere
- Integral of the derivative of a monotone function is bounded by its total increase
- Complex differentiability at a point without local holomorphy
- Removability and the Taylor radius of \(z\cot z\)
- The sharp derivative bound for an upper-half-plane map with \(f(i)=1/2\)
- Harmonic conjugate on the punctured disk up to a logarithmic term
ANALYSIS QUALIFYING EXAM, MAY 2009 (pp. 32–33)
- Meromorphic functions with a logarithmic bound divided by \(|z|\)
- The unique right-half-plane solution of \(z+e^{-z}=2+i\)
- Uniformly convergent holomorphic sequences with a single zero each
- The Fourier transform of \(1/(1+x^2)\) at frequency one
- Convolution of two \(L^2\) functions is bounded and continuous
- Uniform convergence for an approximation to the identity on the circle
- \(L^p\) convergence implies convergence in measure on the unit interval
- Successive moment ratios converge to the essential supremum
PROBLEMS FOR ANALYSIS QUALIFYING EXAM, Fall 2008 (p. 34)
- Iteration of s -> s^2 on [0,1]: pushforward measures and their weak limit
- Integral operators on \(L^p\) via Schur-type bounds
- Separability of the Banach space l-infinity
- \(\int_0^\infty\frac{\log x}{(x^2+4)^2}\,dx\) by residues
- Counting solutions of e^z = 3z^7 in the unit disk
- Entire functions of polynomial growth are polynomials
- Holomorphic bijections onto a simply connected domain agreeing at 0
PROBLEMS FOR ANALYSIS QUALIFYING EXAM, SPRING 2008 (p. 35)
- Convolutions of characteristic functions of finite-measure sets
- \(\|f\|_p\to\|f\|_\infty\) on \([0,1]\), with a counterexample on \(\RR\)
- Absolute convergence of the Fourier series of a C1 periodic function
- Boundedness of an operator on l2 from its matrix coefficients
- Entire functions bounded by a nonvanishing entire function are constant multiples
- Conformal self-maps of the disk agreeing at two points coincide
- A holomorphic function with a double zero takes nearby values at least twice
- Derivative bounds and extremal sequences for families of disk-valued holomorphic maps
ANALYSIS QUALIFYING EXAM, FALL 2007 (p. 36)
- Complex analyticity of a real polynomial via the Cauchy-Riemann equations
- Entire functions bounded by the exponential
- Unit boundary modulus forces at least two annular zeros with multiplicity
- The integral of \(1/(1+x^n)\) by residue calculus
- Membership examples separating \(L^1\) and \(L^2\)
- An open dense subset of R with measure one
- A summably integrable sequence converges to zero almost everywhere
- Compactly supported \(L^1\) convolution need not be uniformly continuous
PROBLEMS FOR ANALYSIS QUALIFYING EXAM, SPRING 2007 (p. 37)
- Zeros of a sextic in the unit disk
- The Poisson kernel integral by residues
- Iterates of a non-rotational disk map vanish at the fixed point
- A surjective holomorphic map from the disk onto \(\mathbb C\)
- Membership of \(1/x\) in \(L^p(0,\infty)\)
- \(L^4\) functions with vanishing \(L^1\) norm converge weakly
- Weakly convergent \(L^2\) sequences with unbounded norms
- A function and its Fourier transform cannot both have compact support
ANALYSIS QUALIFYING EXAM, SEPTEMBER 2006 (pp. 38–39)
- The integral of \(1/(x^4+4)\) by residues
- Hurwitz theorem for uniformly convergent holomorphic sequences with one zero
- Holomorphic maps into the upper half plane and bounded harmonic functions on a slit plane
- Maximal derivative of a disk map into the upper half plane
- Finite-dimensionality of trigonometric-polynomial subspaces of C[0, pi]
- Oscillatory integral is o(1/t) under endpoint vanishing
- \(L^2\) boundedness and vanishing \(L^1\) norm imply weak convergence to \(0\)
- Unique norming point for a functional on a space satisfying the parallelogram inequality
ANALYSIS QUALIFYING EXAM, MAY 2006 (pp. 40–41)
- No holomorphic logarithm of a meromorphic function with a pole
- Zeros of a septic in the disks of radius one and two
- Entire functions bounded by \(|z|^{3/2}\) outside the unit disk
- Monotone harmonic functions converging to the constant one
- Derivative range of a half-plane self-map at a fixed point
- Poles and residues of \(e^{\pi z}/(z^2+1)^2\)
- Separating \(L^1\) and \(L^2\) on \(\RR\) and \((0,1)\)
- \(L^1\cap L^2\subseteq L^p\) for \(1\le p\le2\)
- The Fourier transform of an \(L^1\) function is uniformly continuous and vanishes at infinity
- Translation continuity of \(L^1\) functions on the line
- Boundedness of a weakly convergent sequence in \(L^2([0,1])\)
- Cesaro means of an orthonormal sequence converge to zero a.e.
ANALYSIS QUALIFYING EXAM, SEPTEMBER 2005 (pp. 42–43)
- \(\|f_n\|_2^2\le n^{-2}\) forces \(f_n\to0\) a.e.
- Translation continuity of \(L^1\) functions on the line
- Weak convergence to zero on the circle
- Weak lower semicontinuity of the norm and strong convergence
- The keyhole integral of \(1/(x^{1/3}(1+x))\)
- Automorphisms of the right half-plane and of \(\mathbb C\)
- Zeros of \(z^9+z^5-8z^3-z+2\) between two circles
- Surjective holomorphic maps between the right half-plane and the plane
ANALYSIS QUALIFYING EXAM SPRING 2005 (p. 44)
- Smoothness and decay of the Fourier transform of e^{-|x|}
- An integral operator on L^1[0,1] with kernel 1/t
- \(L^p\) inclusions on finite- and infinite-measure spaces
- Weak and strong convergence of an orthonormal basis and its Cesàro means
- Nonzero C_c^∞ function with compactly supported Fourier transform
- Residue evaluation of a rational-times-sine integral
- Holomorphic bijection from the quadrant to the unit disk
- Zeros equal poles for a meromorphic function with positive real boundary values
Undated analysis exam, closed book, two and a half hours, seven problems (pp. 45–47)
- \(C([0,1])\) is a Banach space; \(\sin nx\) converges weakly to \(0\) in \(L^2\) but not strongly
- Countable additivity of the integral; densities as signed Borel measures; a computed mass
- Direct proof that the Fourier transform of an \(L^1\) function is uniformly continuous and vanishes at infinity
- Integrability of \(\cos x/(1+x^2)\) and evaluation of \(\int_0^\infty\cos x/(1+x^2)\,dx\)
- Nonreal solutions of \(z^3+z^4=2\) in \(|z|<2\)
- Entire functions bounded by \(3\log|z|\) at infinity
- The integral of \(e^z/z^3\) around \(|z-1|=2\)
Undated analysis exam, seven problems, instructions citing the syllabus (pp. 45–47)
- \(g_n(x)=\sin^2(nx)\): pointwise, strong \(L^1\), and weak \(L^1\) convergence
- Maximum of the exponential of the mean log under a mean-one constraint
- Decay, square-integrability, continuity, and boundedness of the Fourier transform of \((1+\xi^2)^{-\alpha}\)
- Residue evaluation of \(f_1(x)=\int_{\mathbb R}(1+\xi^2)^{-1}e^{2\pi i x\xi}\,d\xi\)
- Contour integrals of \(1/f\) at simple and double zeros
- A boundary contraction of the disk has exactly one interior fixed point
- A nonidentity disk automorphism fixing \(1/3\)
Undated analysis exam, two hours, six equally weighted questions (pp. 45–47)
- Absolute continuity of the Lebesgue integral: small-measure sets have small integrals
- Wirtinger’s inequality on \([0,\pi]\) for functions vanishing at the endpoints
- The operator \(Tf(x)=x^{-1/p}\int_0^xf\) maps \(L^q\) boundedly into \(C^0\)
- Zeros of \(2z^5+8z-1\) in \(1<|z|<2\)
- Bergman-type area integral of the derivative on a punctured disk: bounded vs unbounded case
- A positive harmonic function on the punctured plane is constant
SPRING 2003 COMPLEX ANALYSIS QUALIFYING EXAM (p. 48)
Real Analysis Qualifying Exam, Fall 2002 (p. 49)
- A continuous nowhere differentiable function built from the triangle wave
- Monotone convergence for an increasing sequence with bounded integrals
- Equicontinuity and the Arzela-Ascoli theorem on a Sobolev family
- Unique nearest-point projection onto a closed convex subset of a Hilbert space
- The sum of the odd sine series and the Basel problem
Complex Analysis Core Qualifying Exam, Fall 2002 (p. 50)
- Failure of holomorphic and meromorphic extension from an annulus
- Holomorphic and smooth equivalence of an annulus with a punctured disk
- Entire functions bounded by the square of the modulus
- A disk automorphism sending \(1/2\) to \(-1/\pi\)
- Simplicity and small-disk zero count for \(z^7+z^3+1/16\)
- Evaluating \(\int_0^\infty u^2/(u^6+1)\,du\)
Real Analysis Qualifying Exam (p. 51)
- Quantitative Riemann-Lebesgue decay under vanishing endpoint conditions
- A pointwise-convergent subsequence of sine sums with continuous limit
- The \(1/5\)-Hölder norm \(|f(0)|+[f]_{1/5}\) is complete on \([0,1]\)
- A function whose every set-integral is bounded by measure is at most 1 a.e.
- \(\|f\|_p\to\|f\|_\infty\) as \(p\to\infty\) for \(f\in L^1\cap L^\infty\)
- The principal value distribution is the derivative of log |x|
Complex Analysis Core Qualifying Exam, Spring 2002 (p. 52)
- Entire functions whose image omits a ray
- Evaluating \(\int_0^{2\pi}(a^2+\cos^2x)^{-1}\,dx\)
- Classification of simply connected regions in the Riemann sphere
- Even-part Schwarz bound for a normalized disk self-map
- Negative Laurent coefficients of \(1/\sin z\) on \(\pi<|z|<2\pi\)
- Mobius transformations carry lines and circles to lines and circles
Real Analysis Qualifying Exam, Fall 2001 (pp. 53–54)
COMPLEX ANALYSIS CORE QUALIFYING EXAM, FALL 2001 (p. 55)
- Meromorphic functions on the Riemann sphere are rational
- The unique right-half-plane solution of \(z-\alpha=e^{-z}\) is real
- Evaluating \(\int_0^\infty(1+x^3)^{-1}\,dx\)
- Schwarz-Pick: holomorphic self-map of disk maps smaller disks into smaller disks
- Growth bound for a disk map into a vertical strip
REAL ANALYSIS QUALIFYING EXAM, SPRING 2001 (p. 56)
- Mollifier convolutions converge in \(L^p\) but not in \(L^\infty\)
- Absolute continuity of the Lebesgue integral
- Lower semicontinuous functions and lower Riemann sums
- Interpolation inequality between the \(L^{4/3}\), \(L^2\), and \(L^4\) norms
- Integral operators with continuous kernel map the unit ball of C[0,1] to a precompact set
COMPLEX ANALYSIS CORE QUALIFYING EXAM, SPRING 2001 (p. 57)
- An entire function dominated by another is its scalar multiple
- Zeros of \(2z^5+8z-1\) in \(1<|z|<2\)
- Convergence on a dense subset implies pointwise convergence for bounded holomorphic functions
- A positive harmonic function on the punctured plane is constant
- A nonconstant annulus map of constant boundary modulus has at least two zeros
- Gauss–Lucas theorem for polynomial critical points