Let $S$ be an irregular surface of general type over $mathbb{C}$ and $a colon S to A:=textrm{Alb}(S)$ be its Albanese map. Let Def($S$) and Def($A$) be the bases of the Kuranishi family of $S$ and $A$, respectively. Then $a$ induces a map $f colon textrm{Def}(S) to textrm{Def}(A)$, whose differential is $f_* colon H^1(S, T_S) to
H^1(A, T_A)$.
Since every small deformation of $S$ is again a surface of general type, if Def(S) is generically smooth then the image of $f_*$ is contained in the subspace of dimension $frac{g(g+1)}{2}$ of $H^1(A, T_A)$ corresponding to the algebraic deformations of $A$ (here $g := dim(A)$ ).
Is this still true when Def($S$) is not generically smooth, i.e. everywhere non-reduced?
I suspect that the answer should be "yes", but I would like to see a rigorous proof (or a counterexample, if my guess is wrong).
No comments:
Post a Comment