Abstract
Let ℭ be a class of automata (in a precise sense to be defined) and ℭc the class obtained by augmenting each automaton in ℭ with finitely many reversal-bounded counters. We first show that if the languages defined by ℭ are effectively semilinear, then so are the languages defined by ℭc, and, hence, their emptiness problem is decidable. This result is then used to show the decidability of various problems concerning morphisms and commutation of languages. We also prove a surprising undecidability result: given a fixed two element code K, it is undecidable whether a given context-free language L commutes with K, i.e., LK = KL.
Supported under the grant 44087 of the Academy of Finland.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
L. Breveglieri, A. Cherubini, C. Citrini, and S. Crespi Reghizzi. Multiple pushdown languages and grammars. Internat. J. Found. Comput. Sci. 7 (1996), 253–291.
C. Choffrut and J. Karhumäki, Combinatorics of words, in Handbook of Formal Languages, Vol. 1, (A. Salomaa and G. Rozenberg, eds.), Springer-Verlag, 1997, pp. 329–438.
C. Choffrut and J. Karhumäki. Characterizing the subsets of words commuting with a set of two words. Proc. 7th Nordic Combinatorial Conference, Turku, Finland, 1999.
C. Choffrut, J. Karhumäki, and N. Ollinger. The commutation of finite sets: challenging problem. Theoret. Comput. Sci., to appear; TUCS Technical Report 303, http://www.tucs.fi, 1999.
K. Culik II and A. Salomaa. On the decidability of homomorphism equivalence for languages. J. Comput. System Sci. 17, (1978), 163–175.
Z. Dang. Verification and Debugging of Infinite State Real-time Systems. Ph.D. Thesis, University of California, Santa Barbara, 2000.
S. Ginsburg. The Mathematical Theory of Context-Free Languages. McGraw-Hill, New York, 1966.
S. A. Greibach. Checking automata and one-way stack languages. SDC Document TM 738/045/00, 1968.
E. M. Gurari and O. H. Ibarra. The complexity of decision problems for finite-turn multicounter machines. J. Comput. System Sci. 22 (1981), 220–229.
V. Halava and T. Harju. Undecidability in integer weighted finite automata. Fund. Inf. 38 (1999), 189–200.
M. Harrison. Introduction to Formal Language Theory. Addison-Wesley, Reading, Mass., 1978.
S. Horvath, J. Karhumä and H. C. M. Kleijn. Results concerning palindromicity. J. Int. Process. Cyber. EIK 23 (1987), 441–451.
O. H. Ibarra. Reversal-bounded multicounter machines and their decision problems. J. ACM 25 (1978), 116–133.
O. H. Ibarra, T. Bultan, and J. Su. Reachability analysis for some models of infinite-state transition systems. Proc. 10th Int. Conf. on Concurrency Theory, 2000.
O. H. Ibarra, T. Jiang, N. Tran, and H. Wang. New decidability results concerning two-way counter machines. SIAM J. Comput. 24 (1995), 123–137.
J. Karhumäki and L. P. Lisovik. A simple undecidable problem: the inclusion problem for finite substitutions on ab * c. Proc. of the STACS 2001, to appear.
M. Lothaire, Combinatorics on Words, Addison-Wesley, 1983.
R. Parikh. On context-free languages. J. ACM 13 (1966), 570–581.
A. Salomaa. Formal Languages. Academic Press, New York, 1973.
G. Sénizergues. L(A)=L(B)? decidability results from complete formal systems. Theoret. Comput. Sci. 251 (2001), 1–166.
C. Stirling. Decidability of DPDA equivalence. Theoret. Comput. Sci., to appear.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2001 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Harju, T., Ibarra, O., Karhumäki, J., Salomaa, A. (2001). Decision Questions Concerning Semilinearity, Morphisms, and Commutation of Languages. In: Orejas, F., Spirakis, P.G., van Leeuwen, J. (eds) Automata, Languages and Programming. ICALP 2001. Lecture Notes in Computer Science, vol 2076. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-48224-5_48
Download citation
DOI: https://doi.org/10.1007/3-540-48224-5_48
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-42287-7
Online ISBN: 978-3-540-48224-6
eBook Packages: Springer Book Archive