Trace 1, 2×2 matrices over principal ideal domains are exchange

We prove that trace 1 matrices over principal ideal domains are exchange and characterize 2 × 2 exchange matrices over commutative domains. In addition, we emphasize large classes of not exchange 2 × 2 and 3 × 3 integral matrices.

Learning Weighted Automata over Principal Ideal Domains

In this paper, we study active learning algorithms for weighted automata over a semiring. We show that a variant of Angluin’s seminal $$\mathtt {L}^{\!\star }$$ L ⋆ algorithm works when the semiring is a principal ideal domain, but not for general semirings such as the natural numbers.

A Signature-Based Algorithm for Computing Gröbner Bases over Principal Ideal Domains

Signature-based algorithms have become a standard approach for Gröbner basis computations for polynomial systems over fields, but how to extend these techniques to coefficients in general rings is not yet as well understood. In this paper, we present a proof-of-concept signature-based algorithm for computing Gröbner bases over commutative integral domains. It is adapted from a general version of Möller’s algorithm (J Symb Comput 6(2–3), 345–359, 1988) which considers reductions by multiple polynomials at each step. This algorithm performs reductions with non-decreasing signatures, and in particular, signature drops do not occur. When the coefficients are from a principal ideal domain (e.g. the ring of integers or the ring of univariate polynomials over a field), we prove correctness and termination of the algorithm, and we show how to use signature properties to implement classic signature-based criteria to eliminate some redundant reductions. In particular, if the input is a regular sequence, the algorithm operates without any reduction to 0. We have written a toy implementation of the algorithm in Magma. Early experimental results suggest that the algorithm might even be correct and terminate in a more general setting, for polynomials over a unique factorization domain (e.g. the ring of multivariate polynomials over a field or a PID).