Wheeled PROPs, graph complexes and the master equation

We introduce and study wheeled PROPs, an extension of the theory of PROPs which can treat traces and, in particular, solutions to the master equations which involve divergence operators. We construct a dg free wheeled PROP whose representations are in one-to-one correspondence with formal germs of SP-manifolds, key geometric objects in the theory of Batalin-Vilkovisky quantization. We also construct minimal wheeled resolutions If classical operads Corn and Ass as non-trivial extensions of the well-known dg operads Com(infinity) and Ass(infinity). Finally, we apply the above results to a computation of cohomology of a directed version of Kontsevich's complex of ribbon graphs. (C) 2008 Elsevier B.V. All rights reserved.