Abstract: 

Four-dimensional Yang–Mills theory can be obtained from a topological field theory of Schwarz type via a procedure known as BV pushforward, which amounts in integrating out some gauge-fixed fields. This turns out to be an equivalence in the sense that it establishes an isomorphism between the observables of the two theories, which in turns implies that their expectation values can be computed in either theory with the same outcome. I will give an introduction to the basic concept, including the BV pushforward, and discuss in details an easier case.