A bijection for tri-cellular maps

In this paper we give a bijective proof for a relation between uni- bi- and tricellular maps of certain topological genus. While this relation can formally be obtained using Matrix-theory as a result of the Schwinger-Dyson equation, we here present a bijection for the corresponding coefficient equation. Our construction is facilitated by repeated application of a certain cutting, the contraction of edges, incident to two vertices and the deletion of certain edges.