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Abstract : |
We present a concurrent semantics for concurrent constraint (cc) programming framework with both ("committed choice") indeterminism and ("backtracking") nondeterminism. The semantics extends the previous semantics for Indeterminate cc by (1) allowing each state to contain different or-parallel components and (2) splitting the concurrency relation into two to distinguish between andand or-concurrency. Thereby, the construction produces a single representation (an And-or contextual net) that captures the important relationships between events in program runs: concurrency, causal dependency, indeterminism and nondeterminism. We believe this is a first step towards the formal analysis of the concurrent semantics of practical cc languages containing both in- and non-determinism, such as AKL [HJ90]. 1, |
