DMS Algebra Seminar

Speaker: Rankeya Datta (University of Missouri)

Title: Enhancements of flatness in commutative algebra

Abstract: The notion of flatness plays a fundamental role in algebraic geometry and commutative algebra. A basic property of a flat module is that expansion of ideals to the module commutes with intersection for a finite family of ideals. In this talk I will introduce several enhancements of flat modules that arise from examining the natural question of when ideal expansion to a flat module commutes with intersection for an arbitrary (i.e., possibly infinite) family of ideals. These enhancements of flatness were first explored by Raynaud-Gruson in their work on the faithfully flat descent of projectivity and by Ohm-Rush in their work on content functions and trace ideals. Later, Hochster-Huneke encountered these enhancements in their development of tight closure theory in prime characteristic. Most of my talk will focus on defining and exploring these flatness enhancements and how they relate to each other. A particularly pleasing picture emerges in the local setting. If time permits, I will mention consequences for some outstanding questions in prime characteristic singularity theory.