Polynomial complexity despite the fermionic sign

The Complexity of Computing the Sign of the Tutte Polynomial (and Consequent #P-hardness of Approximation)

We study the complexity of computing the sign of the Tutte polynomial of a graph. As there are only three possible outcomes (positive, negative, and zero), this seems at first sight more like a decision problem than a counting problem. Surprisingly, however, there are large regions of the parameter space for which computing the sign of the Tutte polynomial is actually #P-hard. As a trivial cons...

Complexity of the Cover Polynomial

The cover polynomial introduced by Chung and Graham is a twovariate graph polynomial for directed graphs. It counts the (weighted) number of ways to cover a graph with disjoint directed cycles and paths, it is an interpolation between determinant and permanent, and it is believed to be a directed analogue of the Tutte polynomial. Jaeger, Vertigan, and Welsh showed that the Tutte polynomial is #...

Complexity measures of sign matrices

What is complexity, and how should it be studied mathematically? In the interpretation that we adopt, there are several underlying common themes to complexity theories. The basic ground rules are these: There is a family F of some mathematical objects under consideration. The elements of some subset S ⊆F are deemed simple. Also, there are certain composition rules that allow one to put together...

On the Complexity of the Interlace Polynomial

We consider the two-variable interlace polynomial introduced by Arratia, Bollobás and Sorkin (2004). We develop two graph transformations which allow us to derive point-to-point reductions for the interlace polynomial. Exploiting these reductions we obtain new results concerning the computational complexity of evaluating the interlace polynomial at a fixed point. Regarding exact evaluation, we ...

The Complexity of the Minimal Polynomial