Tag 0084
\(D_{7}^{*}\)
D7*
Invariants
| Rank | 7 |
|---|---|
| Signature \((n_+, n_-)\) | (7, 0) |
| Determinant | \(\tfrac{1}{4}\) |
Gram tensor
The components \(b(e_i, e_j)\) of the Gram tensor \(b\) in the chosen basis \(e_{1}, \dots, e_{7}\).
| \(e_{1}\) | \(e_{2}\) | \(e_{3}\) | \(e_{4}\) | \(e_{5}\) | \(e_{6}\) | \(e_{7}\) | |
|---|---|---|---|---|---|---|---|
| \(e_{1}\) | 1 | 1 | 1 | 1 | 1 | 1/2 | 1/2 |
| \(e_{2}\) | 1 | 2 | 2 | 2 | 2 | 1 | 1 |
| \(e_{3}\) | 1 | 2 | 3 | 3 | 3 | 3/2 | 3/2 |
| \(e_{4}\) | 1 | 2 | 3 | 4 | 4 | 2 | 2 |
| \(e_{5}\) | 1 | 2 | 3 | 4 | 5 | 5/2 | 5/2 |
| \(e_{6}\) | 1/2 | 1 | 3/2 | 2 | 5/2 | 7/4 | 5/4 |
| \(e_{7}\) | 1/2 | 1 | 3/2 | 2 | 5/2 | 5/4 | 7/4 |
[[1, 1, 1, 1, 1, 1/2, 1/2], [1, 2, 2, 2, 2, 1, 1], [1, 2, 3, 3, 3, 3/2, 3/2], [1, 2, 3, 4, 4, 2, 2], [1, 2, 3, 4, 5, 5/2, 5/2], [1/2, 1, 3/2, 2, 5/2, 7/4, 5/4], [1/2, 1, 3/2, 2, 5/2, 5/4, 7/4]]
Definite lattice
| Minimum of \(b(x, x)\), \(x \neq 0\) | \(1\) |
|---|---|
| Kissing number | 14 |
| Order of the isometry group | \(645120 = 2^{11} \cdot 3^{2} \cdot 5 \cdot 7\) |
Roots
| Root lattice: \(L = \mathbb{Z}\Phi(L)\) | no |
|---|---|
| Number of roots | 98 |
| \(R(L) = \mathbb{Z}\Phi(L)\) | \(\cong \mathrm{I}_{7,0}\) |
| Rank of \(R(L)\) | 7 |
| \([L : R(L)]\) | 2 |
| \(R(L)\) is primitive in \(L\) | no: \(L / R(L) \cong \mathbb{Z}/2\) |
Components of \(\Phi(L)\)
| Component | Type | Values of \(b(r, r)\) | Number of roots | \(\mathbb{Z}\Phi_c\) |
|---|---|---|---|---|
| \(\Phi_{1}\) | \(B_{7}\) | \(\{1, 2\}\) | 98 | \(\cong \mathrm{I}_{7,0}\) |
Simple roots
| Simple root | Coordinates | \(b(r, r)\) |
|---|---|---|
| \(\alpha_{1}\) | \(e_{2}\) | \(2\) |
| \(\alpha_{2}\) | \(e_{1} - 2e_{2} + e_{3}\) | \(2\) |
| \(\alpha_{3}\) | \(e_{2} - 2e_{3} + e_{4}\) | \(2\) |
| \(\alpha_{4}\) | \(e_{3} - 2e_{4} + e_{5}\) | \(2\) |
| \(\alpha_{5}\) | \(e_{4} - 2e_{5} + e_{6} + e_{7}\) | \(2\) |
| \(\alpha_{6}\) | \(e_{5} - 2e_{6}\) | \(2\) |
| \(\alpha_{7}\) | \(e_{6} - e_{7}\) | \(1\) |