By Topic

The confluence of ground term rewrite systems is decidable in polynomial time

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$33 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

3 Author(s)
Comon, H. ; Stanford Univ., Cachan, France ; Godoy, G. ; Nieuwenhuis, R.

The confluence property of ground (i.e., variable-free) term rewrite systems (GTRS) is well-known to be decidable. This was proved independently by M. Dauchet et al. (1987; 1990) and by M. Oyamaguchi (1987) using tree automata techniques and ground tree transducer techniques (originated from this problem), yielding EXPTIME decision procedures (PSPACE for strings). Since then, it has been a well-known longstanding open question whether this bound is optimal. The authors give a polynomial-time algorithm for deciding the confluence of GTRS, and hence alsofor the particular case of suffix- and prefix string rewrite systems or Thue systems. We show that this bound is optimal for all these problems by proving PTIME-hardness for the string case. This result may have some impact on other areas of formal language theory, and in particular on the theory of tree automata.

Published in:

Foundations of Computer Science, 2001. Proceedings. 42nd IEEE Symposium on

Date of Conference:

8-11 Oct. 2001