Unobstructedness of deformations for a d-semistable central corank one boundary point
Emeryck Marie · Geometriae Dedicata · 2025
Abstract In this paper, we prove the unobstructedness of the functor of log smooth deformations for an irreducible type II degeneration of complex abelian surfaces — shifted gluing of a $$\mathbb {P}^1$$ P 1 -bundle over an elliptic curve along two disjoint sections — using the $$T^1$$ T 1 -lifting technique and the degeneration on the first page of a Hodge–de Rham like spectral sequence for the sheaf of torsion-free differentials. From this result and by comparing the log smooth and ordinary flat deformations at first order of such surfaces, we deduce that the functors of locally trivial and flat deformations of such surfaces are unobstructed; we deduce a smoothability result for such surfaces as well.