On the CRON Conjecture

  • Tom J. Ameloot
  • Jan Van den Bussche
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7494)


Declarative networking is a recent approach to programming distributed applications with languages inspired by Datalog. A recent conjecture posits that the delivery of messages should respect causality if and only if they are used in non-monotone derivations. We present our results about this conjecture in the context of Dedalus, a Datalog-variant for distributed programming. We show that both directions of the conjecture fail under a strong semantical interpretation. But on a more syntactical level, we can show that positive Dedalus programs can tolerate non-causal messages, in the sense that they compute the correct answer when messages can be sent into the past.


Active Node Operational Semantic Database Schema Inductive Rule Database Instance 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Abiteboul, S., Bienvenu, M., Galland, A., et al.: A rule-based language for Web data management. In: Proceedings 30th ACM Symposium on Principles of Database Systems, pp. 293–304. ACM Press (2011)Google Scholar
  2. 2.
    Abiteboul, S., Hull, R., Vianu, V.: Foundations of Databases. Addison-Wesley (1995)Google Scholar
  3. 3.
    Alvaro, P., Ameloot, T.J., Hellerstein, J.M., Marczak, W., Van den Bussche, J.: A declarative semantics for dedalus. Technical Report UCB/EECS-2011-120, EECS Department, University of California, Berkeley (November 2011)Google Scholar
  4. 4.
    Alvaro, P., Marczak, W., et al.: Dedalus: Datalog in time and space. Technical Report EECS-2009-173, University of California, Berkeley (2009)Google Scholar
  5. 5.
    Alvaro, P., Marczak, W.R., Conway, N., Hellerstein, J.M., Maier, D., Sears, R.: Dedalus: Datalog in Time and Space. In: de Moor, O., Gottlob, G., Furche, T., Sellers, A. (eds.) Datalog 2010. LNCS, vol. 6702, pp. 262–281. Springer, Heidelberg (2011)CrossRefGoogle Scholar
  6. 6.
    Ameloot, T.J., Neven, F., Van den Bussche, J.: Relational transducers for declarative networking. In: Proceedings 30th ACM Symposium on Principles of Database Systems, pp. 283–292. ACM Press (2011)Google Scholar
  7. 7.
    Ameloot, T.J., Van den Bussche, J.: Deciding eventual consistency for a simple class of relational transducers. In: Proceedings of the 15th International Conference on Database Theory, pp. 86–98. ACM Press (2012)Google Scholar
  8. 8.
    Apt, K.R., Francez, N., Katz, S.: Appraising fairness in languages for distributed programming. Distributed Computing 2, 226–241 (1988)MATHCrossRefGoogle Scholar
  9. 9.
    Attiya, H., Welch, J.: Distributed Computing: Fundamentals, Simulations, and Advanced Topics. Wiley (2004)Google Scholar
  10. 10.
    Deutsch, A., Sui, L., Vianu, V., Zhou, D.: Verification of communicating data-driven Web services. In: Proceedings 25th ACM Symposium on Principles of Database Systems, pp. 90–99. ACM Press (2006)Google Scholar
  11. 11.
    Francez, N.: Fairness. Springer-Verlag New York, Inc., New York (1986)Google Scholar
  12. 12.
    Gelfond, M., Lifschitz, V.: The stable model semantics for logic programming. In: Proceedings of the Fifth International Conference on Logic Programming, pp. 1070–1080. MIT Press (1988)Google Scholar
  13. 13.
    Grumbach, S., Wang, F.: Netlog, a Rule-Based Language for Distributed Programming. In: Carro, M., Peña, R. (eds.) PADL 2010. LNCS, vol. 5937, pp. 88–103. Springer, Heidelberg (2010)CrossRefGoogle Scholar
  14. 14.
    Hellerstein, J.M.: Datalog redux: experience and conjecture. Video available (under the title The Declarative Imperative) (2010), PODS 2010 keynote http://db.cs.berkeley.edu/jmh/
  15. 15.
    Hellerstein, J.M.: The declarative imperative: experiences and conjectures in distributed logic. SIGMOD Record 39(1), 5–19 (2010)CrossRefGoogle Scholar
  16. 16.
    Lamport, L.: Fairness and hyperfairness. Distributed Computing 13, 239–245 (2000)CrossRefGoogle Scholar
  17. 17.
    Loo, B.T.: et al. Declarative networking. Communications of the ACM 52(11), 87–95 (2009)CrossRefGoogle Scholar
  18. 18.
    Marczak, W., Alvaro, P., Conway, N., Hellerstein, J.M., Maier, D.: Confluence analysis for distributed programs: A model-theoretic approach. Technical Report UCB/EECS-2011-154, EECS Department, University of California, Berkeley (December 2011)Google Scholar
  19. 19.
    Navarro, J.A., Rybalchenko, A.: Operational Semantics for Declarative Networking. In: Gill, A., Swift, T. (eds.) PADL 2009. LNCS, vol. 5418, pp. 76–90. Springer, Heidelberg (2008)CrossRefGoogle Scholar
  20. 20.
    Saccà, D., Zaniolo, C.: Stable models and non-determinism in logic programs with negation. In: Proceedings of the Ninth ACM Symposium on Principles of Database Systems, pp. 205–217. ACM Press (1990)Google Scholar
  21. 21.
    Zhang, Q., Cheng, L., Boutaba, R.: Cloud computing: state-of-the-art and research challenges. Journal of Internet Services and Applications 1, 7–18 (2010)CrossRefGoogle Scholar
  22. 22.
    Zinn, D., Green, T.J., Ludaescher, B.: Win-move is coordination-free. In: Proceedings of the 15th International Conference on Database Theory, pp. 99–113. ACM Press (2012)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Tom J. Ameloot
    • 1
    • 2
  • Jan Van den Bussche
    • 1
    • 2
  1. 1.Hasselt UniversityHasseltBelgium
  2. 2.Transnational University of LimburgBelgium

Personalised recommendations