A space X is discretely absolutely star-Lindelöf if for every open cover U of X and every dense subset D of X, there exists a countable subset F of D such that F is discrete closed in X and St(F, U) = X, where St(F, U) = {U ∈ U : U ∩F = ∅}. We show that every Hausdorff star-Lindelöf space can be represented in a Hausdorff discretely absolutely star-Lindelöf space as a closed G δ-subspace.

The parallel language CSP [H,1985], an earlier version of which was described in [H,1978], has become a major tool for the analysis of structuring methods and proof systems involving paxallellsm. The significance of CSP is in the elegance by which a few simply stated constructs (e.g., sequential and parallel composition, nondeterminlstic choice, concealment, and recursion) lead to a language capable of expressing the full complexity of distributed computing. The difficulty in achieving satisfactory semantic models containing these constructs has been in providing an adequate treatment of nondeterminism, deadlock, and divergence. Fortunately, as a result of an evolutionary development in [

We propose a denotational model for real time concurrent systems, based on the failures model for CSP. The fixed point theory is based on the Banach fixed point theorem for complete metric spaces, since the introduction of time as a measure makes all recursive operators naturally contractive. This frees us from many of the constraints imposed by partial orders on the treatment of nondeterminism and divergence.

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