The Laplacian Permanents and Laplacian Ratios of Trees

Brualdi and Goldwasser characterized the Laplacian permanents of trees. In this paper, we study the Laplacian permanents of trees. We characterize some Laplacian permanents of trees. The Laplacian ratio of G is the Laplacian permanent of G divided by the product of degrees of all vertices. In this paper, we obtain that for any n -vertex caterpillar tree T , there exists an n -vertex caterpillar tree C n such that π( C n )≤π( T ) .