# Contents

## Idea

A $\dagger$-graph is a directed graph equipped for each pair of vertices $x,y$ with an involution $\sigma_{x,y} : V(x,y) \to V(y,x)$.

This is one way to think of undirected graphs.

The notion of $\dagger$-graph is to that of dagger-category as the notion of directed graph is to the ordinary notion of category.

## References

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Revised on July 9, 2010 23:06:13 by Eric Forgy (119.247.164.98)