3 papers
math.AG2022
Deformations of Algebras with 2-Extensions
Leo Herr
We apply the notion of 2-extensions of algebras to the deformation theory of algebras. After standard results on butterflies between 2-extensions, we use this (2, 0)-category to gi…
math.AG2021
Costello's pushforward formula: errata and generalization
Leo Herr, Jonathan Wise
K. Costello's Pushforward Formula is not correct as stated. We verify it holds under an assumption of properness or of a weaker notion we call "purity." We then check many papers t…
math.AG2017
Deformations of Modules Through Butterflies and Gerbes
Leo Herr
Classifying obstructions to the problem of finding extensions between two fixed modules goes back at least to L. Illusie's thesis. Our approach, following in the footsteps of J. Wi…