# Tutte Short Exact Sequences of Graphs

## TL;DR

This paper introduces Tutte-like short exact sequences for modules associated with graphs, linking graph invariants through algebraic and combinatorial methods, and rederives known results about the Tutte polynomial.

## Contribution

It establishes new Tutte short exact sequences for graph modules and derives combinatorial consequences, connecting algebraic invariants to classical graph polynomials.

## Key findings

- Reproves Merino's theorem relating critical polynomial to Tutte polynomial
- Links vanishing invariants of G/e to those of G and G\setminus e
- Provides combinatorial interpretations of algebraic structures

## Abstract

We associate two modules, the $G$-parking critical module and the toppling critical module, to an undirected connected graph $G$. The $G$-parking critical module and the toppling critical module are canonical modules (with suitable twists) of quotient rings of the well-studied $G$-parking function ideal and the toppling ideal, respectively. For each critical module, we establish a Tutte-like short exact sequence relating the modules associated to $G$, an edge contraction $G/e$ and an edge deletion $G \setminus e$ ($e$ is a non-bridge). We obtain purely combinatorial consequences of Tutte short exact sequences. For instance, we reprove a theorem of Merino that the critical polynomial of a graph is an evaluation of its Tutte polynomial, and relate the vanishing of certain combinatorial invariants (the number of acyclic orientations on connected partition graphs satisfying a unique sink property) of $G/e$ to the equality of the corresponding invariants of $G$ and $G \setminus e$.