# Definition:Specific Sign (Mathematical Theory)

## Definition

A specific sign of a mathematical theory is a symbol which is defined according to the use to which the theory is being put.

## Bourbaki Definition

The mathematical theory as defined in Bourbaki's Theory of Sets defines the specific sign of set theory as follows:

The specific signs of the theory of sets are $=, \in, \supset$[1].

## Notes

1. The specific symbol for $\supset$ that Bourbaki uses is in fact a bold, sans-serif, uppercase, backwards $\text{C}$. However, the author of this page has been unable to find an appropriate $\LaTeX$ code which will render this symbol properly.