Abstract
Word equation in a special form X = A, where X is a sequence of variables and A is a sequence of constants, is considered. The problem whether X = A has a solution over a free monoid (pattern- equation problem) is shown to be NP-complete. It is also shown that disjunction of a special type equation systems and conjunction of the general ones can be eliminated. Finally, the case of stuttering equations where the word identity is read modulo x 2 = x is mentioned.
The paper is supported by the Grant Agency of the Czech Republic, grant No. 201/97/0456 and by grant FRVŠ 409/199
Acknowledegments
The authors would like to thank the anonymous referee for pointing out the paper [3].
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Černá, I., Klíma, O., Srba, J. (1999). Pattern Equations and Equations with Stuttering. In: Pavelka, J., Tel, G., Bartošek, M. (eds) SOFSEM’99: Theory and Practice of Informatics. SOFSEM 1999. Lecture Notes in Computer Science, vol 1725. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-47849-3_24
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DOI: https://doi.org/10.1007/3-540-47849-3_24
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