Speaker: Junyan Chu (Kyoto University)
Time: 14:00-15:00, Apr 10, 2026
Venue: room 308, School of Mathematical Sciences (New Building)
The Addition-Deletion theorem and Saito's criterion are two classical and foundational tools for characterizing free arrangements. Recently, there has been growing interest in understanding the algebraic structures of non-free arrangements. It is a natural objective to generalize these classical criteria into broader diagnostic tools for the non-free setting. In particular, Abe recently introduced a significant class of non-free arrangements known as strictly plus-one generated (SPOG) arrangements. He showed that deleting one hyperplane from a free arrangement yields an arrangement that is either free or SPOG. Motivated by this, we present generalized versions of both the Addition-Deletion theorem and Saito's criterion specifically tailored for SPOG arrangements, providing a new algebraic framework to characterize this important post-free class.
