# Theory of proveit.logic.classes¶

A class is a collection of sets. Its members are defined by a shared property. A class need not be a set with a well-defined ordinal rank (for example, the class of ordinals cannot have a ordinal rank and must not be a set if we are to avoid the Burali-Forti paradox).

In [1]:
import proveit
%theory # toggles between interactive and static modes


### Local content of this theory

common expressions axioms theorems demonstrations

### All axioms contained within this theory

This theory contains no axioms directly.