The equivalence problem for single-valued two-way transducers (on NPDTOL languages) is decidable
SIAM Journal on Computing
A note on the reduction of two-way automata to one-way atuomata
Information Processing Letters
Monadic second-order definable graph transductions: a survey
Theoretical Computer Science - Selected papers of the 17th Colloquium on Trees in Algebra and Programming (CAAP '92) and of the European Symposium on Programming (ESOP), Rennes, France, Feb. 1992
Economy of description for single-valued transducers
Information and Computation
Handbook of formal languages, vol. 1
MSO definable string transductions and two-way finite-state transducers
ACM Transactions on Computational Logic (TOCL)
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
Squaring transducers: an efficient procedure for deciding functionality and sequentiality
Theoretical Computer Science
Two-Way Automata with Multiplicity
ICALP '90 Proceedings of the 17th International Colloquium on Automata, Languages and Programming
Elements of Automata Theory
Finite automata and their decision problems
IBM Journal of Research and Development
The reduction of two-way automata to one-way automata
IBM Journal of Research and Development
Streaming transducers for algorithmic verification of single-pass list-processing programs
Proceedings of the 38th annual ACM SIGPLAN-SIGACT symposium on Principles of programming languages
Queries on Xml streams with bounded delay and concurrency
Information and Computation
Constant-memory validation of streaming XML documents against DTDs
ICDT'07 Proceedings of the 11th international conference on Database Theory
Regularity problems for visibly pushdown languages
STACS'06 Proceedings of the 23rd Annual conference on Theoretical Aspects of Computer Science
Regular Transformations of Infinite Strings
LICS '12 Proceedings of the 2012 27th Annual IEEE/ACM Symposium on Logic in Computer Science
Two-way transducers with a two-way output tape
DLT'12 Proceedings of the 16th international conference on Developments in Language Theory
From Two-Way to One-Way Finite State Transducers
LICS '13 Proceedings of the 2013 28th Annual ACM/IEEE Symposium on Logic in Computer Science
From Two-Way to One-Way Finite State Transducers
LICS '13 Proceedings of the 2013 28th Annual ACM/IEEE Symposium on Logic in Computer Science
| Hi-index | 0.00 |
Any two-way finite state automaton is equivalent to some one-way finite state automaton. This well-known result, shown by Rabin and Scott and independently by Shepherd son, states that two-way finite state automata (even non-deterministic) characterize the class of regular languages. It is also known that this result does not extend to finite string transductions: (deterministic) two-way finite state transducers strictly extend the expressive power of (functional) one-way transducers. In particular deterministic two-way transducers capture exactly the class of MSO-transductions of finite strings. In this paper, we address the following definability problem: given a function defined by a two-way finite state transducer, is it definable by a one-way finite state transducer? By extending Rabin and Scott's proof to transductions, we show that this problem is decidable. Our procedure builds a one-way transducer, which is equivalent to the two-way transducer, whenever one exists.