English

Why the equivalence problem for unambiguous grammars has not been solved back in 1966?

Formal Languages and Automata Theory 2022-12-08 v1 Data Structures and Algorithms

Abstract

In 1966, Semenov, by using a technique based on power series, suggested an algorithm that tells apart the languages described by an unambiguous grammar and a DFA. At the first glance, it may appear that the algorithm can be easily modified to yield a full solution of the equivalence problem for unambiguous grammars. This article shows why this hunch is, in fact, incorrect.

Cite

@article{arxiv.2212.03786,
  title  = {Why the equivalence problem for unambiguous grammars has not been solved back in 1966?},
  author = {Vladislav Makarov},
  journal= {arXiv preprint arXiv:2212.03786},
  year   = {2022}
}

Comments

11 pages

R2 v1 2026-06-28T07:24:58.754Z