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#21. Counting Spanning Trees

Published

28 Nov, 2023

(Back to course page.)

Link to Slides · Link to recording: Part 1 and Part 2


Prompts for discussion:

  1. We spent time on the determinant of the Laplacian of a graph here (short of one vertex). Is there a structural interpretation of the determinant of the adjacency matrix? There are some thoughts here.

  2. Graham and Pollak showed that the determinant of the distance matrix of a tree TTT on nnn vertices - the n×nn \times nn×n matrix whose each (v,w)∈V(T)×V(T)(v, w) \in V(T) \times V(T)(v,w)∈V(T)×V(T) entry is the ordinary graph distance between vvv and www-depends only on nnn. In fact, they gave a formula: −(n−1)(−2)n−2-(n-1)(-2)^{n-2}−(n−1)(−2)n−2. I thought this was really neat: the determinant seems to be completely independent of the structure of the tree! 🤯


© 2022 • Neeldhara Misra • Credits •

 

Corrections? Please leave a comment here or a PR in this repository, thanks!

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