Many unconditional cases of the Hodge conjecture for abelian varieties beyond divisor classes come from Weil classes for imaginary quadratic fields. We determin
We prove the Hodge conjecture for every product $S_1^{a_1}\times\cdots\times S_r^{a_r}$ of projective K3 surfaces with Picard number at least 17, under one cond
We study $\xi_{44}$ in the K3 representation. Up to standard cycles it is the join $b*(-c)$ of surface characters $b=(4,5,13,22)$, $c=(3,7,11,23)$ whose orbits
We prove HC for all powers of the very general member of new families of abelian varieties with Hodge rings not generated by divisors. For the dicyclic group Di
A preprint of 30 Sep 2026 (OpenAI; not refereed) claims HC and GHC for all powers of K3 surfaces whose transcendental space embeds in $V_P=(U^2\oplus\langle-1\r
For every squarefree $d>1$ we give one-parameter families of projective K3 surfaces of very general Picard number 16 with real multiplication by $\mathbf Q(\sqr
Cubic tenfolds are the first cubic hypersurfaces for which the rational Hodge conjecture (HC) is open in the middle degree. For Thom–Sebastiani tenfolds $X=V(g(
For connected finite Galois covers of complex curves, we construct algebraic determinant classes of every irreducible multiplicity space whenever the branch con
HC for all powers of a projective K3 surface $S$ is known when $T(S)_{\mathbf Q}$ lies in Floccari's locus; for endomorphism field $E=\mathbf Q$ this means $\rh
Markman's secant-sheaf programme proves algebraicity of Weil classes on abelian $2n$-folds once a sheaf on an abelian $n$-fold, with Chern character on a secant
Positivity cannot obstruct the Hodge conjecture on projective varieties, since $\alpha+Nh^p$ is strictly positive for $N\gg0$. It can separate projective from K