Mathai–Quillen formalism

The Mathai-Quillen formalism is a mathematical framework used in the study of characteristic classes and the index theory of elliptic operators, particularly in the context of differential geometry and topology. It provides a method to compute certain invariants associated with fiber bundles, particularly in the setting of oriented Riemannian manifolds. The key ideas behind the Mathai-Quillen formalism involve combining concepts from differential geometry, topology, and algebraic topology, particularly characteristic classes.