
arXiv: 1010.1113
The permanental polynomial of a graph $G$ is $��(G,x)\triangleq\mathrm{per}(xI-A(G))$. From the result that a bipartite graph $G$ admits an orientation $G^e$ such that every cycle is oddly oriented if and only if it contains no even subdivision of $K_{2,3}$, Yan and Zhang showed that the permanental polynomial of such a bipartite graph $G$ can be expressed as the characteristic polynomial of the skew adjacency matrix $A(G^e)$. In this paper we first prove that this equality holds only if the bipartite graph $G$ contains no even subdivision of $K_{2,3}$. Then we prove that such bipartite graphs are planar. Further we mainly show that a 2-connected bipartite graph contains no even subdivision of $K_{2,3}$ if and only if it is planar 1-cycle resonant. This implies that each cycle is oddly oriented in any Pfaffian orientation of a 2-connected bipartite graph containing no even subdivision of $K_{2,3}$. As applications, permanental polynomials for some types of bipartite graphs are computed.
17 pages, 5 figures
1-cycle resonant, Graphs and linear algebra (matrices, eigenvalues, etc.), Pfaffian orientation, Determinant, determinant, permanent, permanental polynomial, 05C31, 05C70, 05C30, 05C75, FOS: Mathematics, Permanent, Mathematics - Combinatorics, Permanental polynomial, Combinatorics (math.CO)
1-cycle resonant, Graphs and linear algebra (matrices, eigenvalues, etc.), Pfaffian orientation, Determinant, determinant, permanent, permanental polynomial, 05C31, 05C70, 05C30, 05C75, FOS: Mathematics, Permanent, Mathematics - Combinatorics, Permanental polynomial, Combinatorics (math.CO)
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