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arXiv 2302.06295math.RAcs.DS
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计算有限展示半群与幺半群的有限指数同余

Computing finite index congruences of finitely presented semigroups and monoids

Marina Anagnostopoulou-Merkouri, Reinis Cirpons, James D. Mitchell, Maria Tsalakou

AI总结:

本文提出两种计算有限展示半群或幺半群有限指数同余的算法,通过推广Sims低指数子群算法及利用相对Green关系理论减少主同余生成数量,并在GAP包和C++库中实现。

摘要:

在本文中,我们描述了一种算法,用于计算具有有限多个类的有限展示半群或幺半群的左同余、右同余或双侧同余,并在有限展示半群或幺半群为有限时提出了一种替代算法。我们将这两种提出的算法与现有算法和实现进行了比较。第一种算法是Sims低指数子群算法的推广,用于寻找幺半群的同余。第二种算法涉及确定不同的主同余,然后找出它们所有可能的并。该算法的变体已被众多作者在众多情境中提出。我们展示了如何利用相对Green关系理论以及幺半群版本的Schreier引理,来减少作为该方法第一步必须生成的主同余数量。本文描述的两种算法均在GAP包Semigroups中实现,第一种算法还在C++库libsemigroups及其Python绑定libsemigroups_pybind11中可用。

英文摘要:

In this paper, we describe an algorithm for computing the left, right, or 2-sided congruences of a finitely presented semigroup or monoid with finitely many classes, and an alternative algorithm when the finitely presented semigroup or monoid is finite. We compare the two algorithms presented with existing algorithms and implementations. The first algorithm is a generalization of Sims' low-index subgroup algorithm for finding the congruences of a monoid. The second algorithm involves determining the distinct principal congruences, and then finding all of their possible joins. Variations of this algorithm have been suggested in numerous contexts by numerous authors. We show how to utilize the theory of relative Green's relations, and a version of Schreier's Lemma for monoids, to reduce the number of principal congruences that must be generated as the first step of this approach. Both of the algorithms described in this paper are implemented in the GAP package Semigroups, and the first algorithm is available in the C++ library libsemigroups and in its python bindings libsemigroups_pybind11.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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