We present two splitting formulas for calculating the Tutte polynomial of a matroid. The first one is for a generalized parallel connection across a 3-point line of two matroids and the second one is applicable to a 3-sum of two matroids. An important tool used is the bipointed Tutte polynomial of a
Tutte polynomials for trees
β Scribed by Sharad Chaudhary; Gary Gordon
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 682 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
β¦ Synopsis
Abstract
We define two twoβvariable polynomials for rooted trees and one twoβvariable polynomial for unrooted trees, all of which are based on the coranknullity formulation of the Tutte polynomial of a graph or matroid. For the rooted polynomials, we show that the polynomial completely determines the rooted tree, i.e., rooted trees T~1~ and T~2~ are isomorphic if and only if f(T~1~) = f(T~2~). The corresponding question is open in the unrooted case, although we can reconstruct the degree sequence, number of subtrees of size k for all k, and the number of paths of length k for all k from the (unrooted) polynomial. The key difference between these three polynomials and the standard Tutte polynomial is the rank function used; we use pruning and branching ranks to define the polynomials. We also give a subtree expansion of the polynomials and a deletionβcontraction recursion they satisfy.
π SIMILAR VOLUMES
This is a close approximation to the content of my lecture. After a brief survey of well known properties, I present some new interpretations relating to random graphs, lattice point enumeration, and chip firing games. I then examine complexity issues and concentrate in particular, on the existence
For any matroid M realizable over Q , we give a combinatorial interpretation of the Tutte polynomial T M (x, y) which generalizes many of its known interpretations and specializations, including Tutte's coloring and flow interpretations of T M (1t, 0), T M (0, 1t); Crapo and Rota's finite field inte
Following Crapo [2], let `(x, y)(M)=x r(M) y r(M\*) , where K=Z[x, y]. Lemma 1. `(x, y) &1 =`(&x, &y).