Detection of global predicates: techniques and their limitations

  • Authors:

  • Craig M. Chase;Vijay K. Garg

  • Affiliations:

  • Parallel and Distributed Systems Laboratory and Electrical and Computer Engineering Department, The University of Texas at Austin, Austin, TX;Parallel and Distributed Systems Laboratory and Electrical and Computer Engineering Department, The University of Texas at Austin, Austin, TX

  • Venue:
  • Distributed Computing
  • Year:
  • 1998

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Abstract

We show that the problem of predicate detection in distributed systems is NP-complete. In the past, efficient algorithms have been developed for special classes of predicates such as stable predicates, observer independent predicates, and conjunctive predicates. We introduce a class of predicates, semi-linear predicates, which properly contains all of the above classes. We first discuss stable, observer independent and semi-linear classes of predicates and their relationships with each other. We also study closure properties of these classes with respect to conjunction and disjunction. Finally, we discuss algorithms for detection of predicates in these classes. We provide a nondeterministic detection algorithm for each class of predicate. We show that each class can be equivalently characterized by the degree of non-determinism present in the algorithm. Stable predicates are defined as those that can be detected by an algorithm with the most non-determinism. All other classes can be derived by appropriately constraining the non-determinism in this algorithm.