An extension theorem in terms of adjoint ideal sheaves

Abstract

In the context of the study of the Ohsawa--Takegoshi $L^2$ extension theorem, a "qualitative" extension theorem in terms of adjoint ideal sheaves (i.e. extension result without $L^2$ estimates but with some form of local $L^2$ condition ensured) is proved on compact Kähler manifolds via harmonic theory and residue computations. The arguments are adapted from those in the study of the injectivity theorem by Chan--Choi--Matsumura. The result guarantees, in particular, the existence of extensions of line-bundle-valued holomorphic top forms over the union of any log-canonical centres of the same codimension to top forms over the ambient space under suitable positivity assumptions.

16 pages; article in the Proceedings of ICFIDCAA 2024