The determinant of q-distance matrices of trees and two quantities   relating to permutations
  In this paper we prove that two quantities relating to the length of permutations defined on trees are independent of the structures of trees. We also find that these results are closely related to the results obtained by Graham and Pollak (Bell System Tech. J. 50(1971) 2495--2519) and by Bapat, Kirkland, and Neumann (Linear Alg. Appl. 401(2005) 193--209). 
Weigen Yan, Yeong-Nan Yeh