# On faithfulness of the lifting for Hopf algebras and fusion categories

## TL;DR

This paper proves the faithfulness of lifting semisimple cosemisimple Hopf algebras and fusion categories from characteristic p to zero, ensuring isomorphisms can be reduced modulo p and analyzing related categorical structures.

## Contribution

It establishes the faithfulness of the lifting process for certain algebraic and categorical structures, filling a gap in prior work and analyzing functorial properties.

## Key findings

- Lifting of semisimple cosemisimple Hopf algebras is fully faithful.
- Lifting induces isomorphisms on Picard and Brauer-Picard groups.
- Subcategories of separable multifusion categories are separable.

## Abstract

We use a version of Haboush's theorem over complete local Noetherian rings to prove faithfulness of the lifting for semisimple cosemisimple Hopf algebras and separable (braided, symmetric) fusion categories from characteristic $p$ to characteristic zero (arXiv/math:0203060, Section 9), showing that, moreover, any isomorphism between such structures can be reduced modulo $p$. This fills a gap in arXiv/math:0203060, Subsection 9.3. We also show that lifting of semisimple cosemisimple Hopf algebras is a fully faithful functor, and prove that lifting induces an isomorphism on Picard and Brauer-Picard groups. Finally, we show that a subcategory or quotient category of a separable multifusion category is separable (resolving an open question from arXiv/math:0203060, Subsection 9.4), and use this to show that certain classes of tensor functors between lifts of separable categories to characteristic zero can be reduced modulo $p$.