Glushkov's construction for functional subsequential transducers
This work provides an incremental optimization for developers and researchers working with regular expression compilers for multitape transducers, focusing on compactness and evaluation efficiency.
The paper tackled the problem of efficiently converting a special flavor of regular expressions into compact functional subsequential weighted finite state transducers, resulting in automata with only one state per input symbol and one transition per symbol range, enabling efficient binary search lookup during evaluation.
Glushkov's construction has many interesting properties and they become even more evident when applied to transducers. This article strives to show the wast range of possible extensions and optimisations for this algorithm. Special flavour of regular expressions is introduced, which can be efficiently converted to $ε$-free functional subsequential weighted finite state transducers. Produced automata are very compact, as they contain only one state for each symbol (from input alphabet) of original expression and only one transition for each range of symbols, no matter how large. Such compactified ranges of transitions allow for efficient binary search lookup during automaton evaluation. All the methods and algorithms presented here were used to implement open-source compiler of regular expressions for multitape transducers.