Five Determinisation Algorithms

Determinisation of nondeterministic finite automata is a well-studied problem that plays an important role in compiler theory and system verification. In the latter field, one often encounters automata consisting of millions or even billions of states. On such input, the memory usage of analysis tools becomes the major bottleneck. In this paper we present several determinisation algorithms, all variants of the well-known subset construction, that aim to reduce memory usage and produce smaller output automata. One of them produces automata that are already minimal. We apply our algorithms to determinise automata that describe the possible sequences appearing after a fixed-length run of cellular automaton 110, and obtain a significant improvement in both memory and time efficiency.