$\mathrm{C}_{6}$ in dimension 4
This tangent representation satisfies the necessary conditions for a hyperelliptic fourfold, but it is not known whether it is realized by an actual variety. See completeness in dimension 4.
- holonomy group
- $\mathrm{C}_{6}$, order $6$, SmallGroup $[6,2]$ · character table
- tangent representation $\rho$
- $\rho(g_{1}) = \operatorname{diag}(1, 1, 1, -1)$$\rho(g_{2}) = \operatorname{diag}(1, 1, 1, \zeta_{3})$
- order of $\omega_X$
- 6
- number of moduli
- 9
- irregularity $q = \dim \operatorname{Aut}^0(X)$
- 3
- Albanese
- the Albanese variety has dimension $3$; the general fiber has dimension $1$ and is an elliptic curve (details)
- $\mathbf{D}^{\mathrm{b}}(X)$
- indecomposable
- Hochschild cohomology $\dim \mathrm{HH}^\bullet$
- $(1, 6, 15, 20, 15, 6, 1, 0, 0)$
Hodge diamond
1
3 3
3 10 3
1 12 12 1
0 6 18 6 0
1 12 12 1
3 10 3
3 3
1
3 3
3 10 3
1 12 12 1
0 6 18 6 0
1 12 12 1
3 10 3
3 3
1
polyvector fields $\mathrm{H}^q(X,\bigwedge^p T_X)$
1
33
393
1991
03930
0330
010
00
0
33
393
1991
03930
0330
010
00
0
twisted Hodge numbers $\mathrm{h}^{p,q}(X,\omega_X^{\otimes j})$
Since $\operatorname{ord} \omega_X = 6$, the twists by powers of the canonical bundle form a finite package of $6$ diamonds (explained).
$\omega_X^{\otimes 0}$
1
33
3103
112121
061860
112121
3103
33
1
33
3103
112121
061860
112121
3103
33
1
$\omega_X^{\otimes 1}$
0
01
033
0393
01991
0393
033
01
0
01
033
0393
01991
0393
033
01
0
$\omega_X^{\otimes 2}$
0
00
000
0000
00000
0000
000
00
0
00
000
0000
00000
0000
000
00
0
$\omega_X^{\otimes 3}$
0
00
000
0000
00000
0000
000
00
0
00
000
0000
00000
0000
000
00
0
$\omega_X^{\otimes 4}$
0
00
000
0000
00000
0000
000
00
0
00
000
0000
00000
0000
000
00
0
$\omega_X^{\otimes 5}$
0
10
330
3930
19910
3930
330
10
0
10
330
3930
19910
3930
330
10
0
References
- A. Demleitner, The classification of hyperelliptic groups in dimension 4. arXiv:2211.07998
- A. Demleitner, C. Gleissner, The classification of rigid hyperelliptic fourfolds, Ann. Mat. Pura Appl. (4) 202 (2023) 1425–1450. MR4576947 doi
- P. Belmans, A. Demleitner, P. Núñez, The Albanese morphism for hyperelliptic varieties, Indag. Math. (N.S.) 37 (2026) 1450–1475. MR5103244 doi