一句话:证明 Kleene allegories 等式理论可判定且为 EXPSPACE 完全,并用图上偏导数给出自动机构造。
本文研究 Kleene allegories 的等式理论可判定性。此前 Brunet 与 Pous 在 LICS 2015 证明了无恒等关系的关系 Kleene 格(Kleene allegories 的一个片段)的等式理论可在 EXPSPACE 内判定,但完整 Kleene allegories 的等式理论是否可判定仍是公开问题。作者通过将字符串上的 Antimirov 偏导数推广到图上,定义图上偏导数,并据此给出类似正则表达式的有限自动机构造算法。该构造为 Kleene allegories 的等式理论提供了判定程序,证明其可判定,并进一步确立其 EXPSPACE 完全性,从而回答了 Brunet 与 Pous 提出的首个公开问题。
Brunet and Pous showed at LICS 2015 that the equational theory of identity-free relational Kleene lattices (a fragment of Kleene allegories) is decidable in EXPSPACE. In this paper, we show that the equational theory of Kleene allegories is decidable, and is EXPSPACE-complete, answering the first open question posed by their work. The proof proceeds by designing partial derivatives on graphs, which are generalizations of partial derivatives on strings for regular expressions, called Antimirov's partial derivatives. The partial derivatives on graphs give a finite automata construction algorithm as with the partial derivatives on strings.