Research paper

Generalized diagram categories and monoids, and their representations

A unified family of diagram categories and monoids, built from cobordism-style pictures with extra twists.

diagrammaticsmonoidsrepresentation theoryGaussian behavior

Data

  • Title: Generalized diagram categories and monoids, and their representations
  • Authors: Matthias Fresacher, Willow Stewart and Daniel Tubbenhauer
  • Status: preprint. Last update: Fri, 19 Dec 2025 02:32:14 UTC
  • arXiv: https://arxiv.org/abs/2512.17177

Abstract

Classical diagram categories and monoids, including the Temperley–Lieb, Brauer, and partition cases, arise as special instances of the category of two-dimensional cobordisms and admit additional twists that produce a large new family of diagram categories and monoids. In this paper we introduce this family and develop a unified approach to their representation theory.

What is the point?

Many diagram algebras look different on the surface, but they are variants of the same basic idea: compose pictures and study the resulting algebra. This paper enlarges the menu of possible pictures and then asks how their representations behave.

Unification:
many classical diagram categories at once.
Twists:
new diagrammatic ingredients.
Statistics:
large families show Gaussian-type behaviour.

A picture

In large generality, the representation theory shows familiar asymptotic shapes.

Gaussian style representation behaviour