Abstract
Previous results on confluence for Constraint Handling Rules, CHR, are generalized to take into account user-defined state equivalence relations. This allows a much larger class of programs to enjoy the advantages of confluence, which include various optimization techniques and simplified correctness proofs. A new operational semantics for CHR is introduced that significantly reduces notational overhead and allows to consider confluence for programs with extra-logical and incomplete built-in predicates. Proofs of confluence are demonstrated for programs with redundant data representation, e.g., sets-as-lists, for dynamic programming algorithms with pruning as well as a Union-Find program, which are not covered by previous confluence notions for CHR.
M.H. Kirkeby—The second author’s contribution has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no 318337, ENTRA - Whole-Systems Energy Transparency.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsNotes
- 1.
It may be the case that \(\pi '_1\) was produced and pruned at an earlier stage, so the propagation history prevents the creation of \(\pi '_1\) anew. A detailed argument can show, that in this case, there will be another constraints \(\pi ''_1\) in the store similar to \(\pi '_1\) but with a \(\ge \) probability, and \(\pi ''_1\) can be used for pruning \(\pi '_2\) and obtain the desired result in that way.
References
Abdennadher, S.: Operational semantics and confluence of constraint propagation rules. In: Smolka, G. (ed.) CP 1997. LNCS, vol. 1330, pp. 252–266. Springer, Heidelberg (1997)
Abdennadher, S., Frühwirth, T.W., Meuss, H.: On confluence ofconstraint handling rules. In: Freuder, E.C. (ed.) CP 1996. LNCS, vol. 1118, pp. 1–15. Springer, Heidelberg (1996)
Aho, A.V., Sethi, R., Ullman, J.D.: Code optimization and finite Church-Rosser systems. In: Rustin, R. (ed.) Design and Optimization of Compilers, pp. 89–106. Prentice-Hall, Englewood Cliffs (1972)
Christiansen, H., Have, C.T., Lassen, O.T., Petit, M.: The Viterbi algorithm expressed in Constraint Handling Rules. In: Van Weert, P., De Koninck, L. (eds.) Proceedings of the 7th International Workshop on Constraint Handling Rules. Report CW 588, pp. 17–24. Katholieke Universiteit Leuven, Belgium (2010)
Duck, G.J., Stuckey, P.J., García de la Banda, M., Holzbaur, C.: The refined operational semantics of constraint handling rules. In: Bart, D., Vladimir, L. (eds.) ICLP 2004. LNCS, vol. 3132, pp. 90–104. Springer, Heidelberg (2004)
Duck, G.J., Stuckey, P.J., Sulzmann, M.: Observable confluence for constraint handling rules. In: Dahl, V., Niemelä, I. (eds.) ICLP 2007. LNCS, vol. 4670, pp. 224–239. Springer, Heidelberg (2007)
Durbin, R., Eddy, S., Krogh, A., Mitchison, G.: Biological Sequence Analysis: Probabilistic Models of Proteins and Nucleic Acids. Cambridge University Press, Cambridge (1999)
Frühwirth, T.W.: Theory and practice of Constraint Handling Rules. J. Logic Progr. 37(1–3), 95–138 (1998)
Frühwirth, T.W.: Constraint Handling Rules. Cambridge University Press, Cambridge (2009)
Haemmerlé, R.: Diagrammatic confluence for Constraint Handling Rules. TPLP 12(4–5), 737–753 (2012)
Huet, G.P.: Confluent reductions: abstract properties and applications to term rewriting systems: abstract properties and applications to term rewriting systems. J. ACM 27(4), 797–821 (1980)
Langbein, J., Raiser, F., Frühwirth, T.W.: A state equivalence and confluence checker for CHRs. In: Weert, P.V., Koninck, L.D. (eds.) Proceedings of the 7th International Workshop on Constraint Handling Rules. Report CW 588, pp. 1–8. Katholieke Universiteit Leuven, Belgium (2010)
Newman, M.: On theories with a combinatorial definition of “equivalence”. Ann. Math. 43(2), 223–243 (1942)
Raiser, F., Betz, H., Frühwirth, T.W.: Equivalence of CHR states revisited. In: Raiser, F., Sneyers, J. (eds.) Proceedings of the 6th International Workshop on Constraint Handling Rules, Report CW 555, pp. 33–48. Katholieke Universiteit Leuven, Belgium (2009)
Raiser, F., Tacchella, P.: On confluence of non-terminating CHR programs. In: Djelloul, K., Duck, G.J., Sulzmann, M. (eds.) CHR 2007, pp. 63–76. Porto, Portugal (2007)
Schrijvers, T., Frühwirth, T.W.: Analysing the CHR implementation of union-find. In: Wolf, A., Frühwirth, T.W., Meister, M. (eds.) W(C)LP. Ulmer Informatik-Berichte, vol. 2005-01, pp. 135–146. Universität Ulm, Ulm (2005)
Sethi, R.: Testing for the Church-Rosser property. J. ACM 21(4), 671–679 (1974)
Sneyers, J., Weert, P.V., Schrijvers, T., Koninck, L.D.: As time goes by: Constraint Handling Rules. TPLP 10(1), 1–47 (2010)
Tarjan, R.E., van Leeuwen, J.: Worst-case analysis of set union algorithms. J. ACM 31(2), 245–281 (1984)
Viterbi, A.J.: Error bounds for convolutional codes and an asymptotically optimum decoding algorithm. IEEE Trans. Inform. Theory 13, 260–269 (1967)
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2015 Springer International Publishing Switzerland
About this paper
Cite this paper
Christiansen, H., Kirkeby, M.H. (2015). Confluence Modulo Equivalence in Constraint Handling Rules. In: Proietti, M., Seki, H. (eds) Logic-Based Program Synthesis and Transformation. LOPSTR 2014. Lecture Notes in Computer Science(), vol 8981. Springer, Cham. https://doi.org/10.1007/978-3-319-17822-6_3
Download citation
DOI: https://doi.org/10.1007/978-3-319-17822-6_3
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-17821-9
Online ISBN: 978-3-319-17822-6
eBook Packages: Computer ScienceComputer Science (R0)