D-brane seminar：Categorical smooth compactifications and generalized Hodge-to-de Rham degeneration
报告人：Alexander Efimov（Steklov Institute/Laboratory for Mirror Symmetry and Automorphic Forms, HSE）
时间：2020-06-10 16:00-18:00
地点：ZOOM conference
Abstract: We disprove two (unpublished) conjectures of Kontsevich which state generalized versions of categorical Hodge-to-de Rham degeneration for smooth and for proper DG categories (but not smooth and proper, in which case degeneration is proved by Kaledin). In particular, we show that there exists a minimal $10$-dimensional $A_{\infty}$-algebra over a field of characteristic zero, for which the supertrace of $\mu_3$ on the second argument is non-zero.
As a byproduct, we obtain an example of a homotopically finitely presented DG category (over a field of characteristic zero) that does not have a smooth categorical compactification, giving a negative answer to a question of To\"en.
This can be interpreted as a lack of resolution of singularities in the noncommutative setup.We also obtain an example of a proper DG category which does not admit a categorical resolution of singularities in the terminology of Kuznetsov and Lunts (that is, it cannot be embedded into a smooth and proper DG category).
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