Generalizations of Checking Stack Automata: Characterizations and Hierarchies

TL;DR

This paper explores various generalized checking stack automata with multiple input heads and stacks, establishing their computational capabilities, hierarchies, and complexity properties, thereby expanding existing theoretical frameworks.

Contribution

It introduces new characterizations and hierarchies for generalized checking stack automata, linking them to multi-head finite automata and space-bounded Turing machines.

Findings

Hierarchies in computational power for different models

Connections between automata models and Turing machine complexity

Decidability and complexity results for the models

Abstract

We examine different generalizations of checking stack automata by allowing multiple input heads and multiple stacks, and characterize their computing power in terms of two-way multi-head finite automata and space-bounded Turing machines. For various models, we obtain hierarchies in terms of their computing power. Our characterizations and hierarchies expand or tighten some previously known results. We also discuss some decidability questions and the space/time complexity of the models.