# nLab Grpd

category theory

## Theorems

### categories of categories

$(n+1,r+1)$-categories of (n,r)-categories

# Contents

## Definition

The (2,1)-category $Grpd$ is the 2-category whose

This is the full sub-2-category of Cat on those categories that are groupoids.

## Properties

### Presentation

One may regard $Grpd$ also just as a 1-category by ignoring the natural isomorphisms between functors. This 1-category may be equipped with the natural model structure on groupoids to provide a 1-categorical presentation of the full $(2,1)$-category.

category: category

Revised on March 10, 2014 06:53:53 by Anonymous Coward (92.140.114.215)