The Hardness of Solving Simple Word Equations
نویسندگان
چکیده
We investigate the class of regular-ordered word equations. The sides of such an equation contain both exactly the same variables, occurring in the same order (but separated by potentially distinct constant factors). Surprisingly, we obtain that solving even such simple equations is NP-hard. By considerations regarding the combinatorial structure of the minimal solutions of the more general quadratic equations we obtain that the satisfiability problem for regular-ordered equations is in NP. Finally, a series of related arguments allow us to show that a related class of simple word equations, that generalises one-variable equations, is in P. 1998 ACM Subject Classification F.2.2, F.4.3
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