  Topological gravity is equivalent to physical gravity in two dimensions in a
way that is still mysterious, though by now it has been proved by Kontsevich.
In this paper it is shown that a similar relation between topological and
physical Yang-Mills theory holds in two dimensions; in this case, however, the
relation can be explained by a direct mapping between the two path integrals.
This (1) explains many strange facts about two dimensional Yang-Mills theory,
like the way the partition function can be expressed exactly as a sum over
classical solutions, including unstable ones; (2) makes the corresponding
topological theory completely computable.
