Are small categories necessarily free?

57 Views Asked by At

In the same spirit that all vector spaces are free, is any small category a free category?. If not, there is a counterexample? I'm interested to know if diagrams indexed by quivers covers all cases of diagrams indexed by small categories.

1

There are 1 best solutions below

0
On BEST ANSWER

A category is small if it's collection of objects and collection of arrows are honest sincere sets. This says nothing about relations among arrows, which decides if a category is free. For a tiny counterexample consider a category with a single object $X$ and with two arrows $\mathrm{id}_X$ and $a$ where $a \circ a = \mathrm{id}_X$.