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The main purpose of this book is to bring together much of the research conducted in recent years in a subject I find both fascinating and impor tant, namely fairness. Much of the reported research is still in the form of technical reports, theses and conference papers, and only a small part has already appeared in the formal scientific journal literature. Fairness is one of those concepts that can intuitively be explained very brieft.y, but bear a lot of consequences, both in theory and the practicality of programming languages. Scientists have traditionally been attracted to studying such concepts. However, a rigorous study of the concept needs a lot of detailed development, evoking much machinery of both mathemat ics and computer science. I am fully aware of the fact that this field of research still lacks matu rity, as does the whole subject of theoretical studies of concurrency and nondeterminism. One symptom of this lack of maturity is the proliferation of models used by the research community to discuss these issues, a variety lacking the invariance property present, for example, in universal formalisms for sequential computing.
List of contents
0 Introduction.- 0.1 Motivation and Background.- 0.2 A Taxonomy of Fairness Concepts.- 0.3 The Language of Guarded Commands (GC).- 1 Termination and Well-Foundedness.- 1.0 Overview.- 1.1 Termination Proofs for Deterministic Programs.- 1.2 Termination Proofs for Nondeterministic Programs.- 2 The Method of Helpful Directions.- 2.0 Introduction to Fair Termination.- 2.1 Ordinal Directed Choice of Helpful Directions.- 2.2 State Directed Choice of Helpful Directions.- 2.3 Inter-reducibility of the Two Methods.- 2.4 Relativized Fair Termination.- 3 The Method of Explicit Scheduler.- 3.0 Overview.- 3.1 Unconditionally-Fair Termination.- 3.2 Weak and Strong Fairness: n Guards.- 3.3 All-Levels Fairness.- 3.4 Comparing Explicit Scheduler with Helpful Directions.- 3.5 More on Fairness and Random Assignments.- 4 Extension and Generalizations of Fairness.- 4.0 Overview.- 4.1 Equifairness.- 4.2 Generalized Fairness.- 4.3 Extreme Fairness.- 4.4 An Analysis of Predicate-Reachability Fairness.- 5 Fair Termination of Concurrent Processes.- 5.1 Overview.- 5.2 Fairness and Communicating Processes.- 5.3 Fairness in Shared-Variables Concurrency.- 6 Syntactic Expressibility.- 6.0 Overview.- 6.1 Fixedpoints of Monotone Transformations.- 6.2 The Assertion Language L?.- 6.3 The Weakest Precondition for Fair Termination.- 6.4 Syntactic Completeness of the SFT Rule.- 6.5 The Ordinal Size for Fair-Termination Proofs.- 7 Fairness in Temporal Logic.- 7.0 Overview.- 7.1 Linear-Time Temporal-Logic (LTL).- 7.2 Branching-Time Temporal-Logics (BTL).- 8 The Functional Approach.- 8.0 Overview.- 8.1 CCS.- 8.2 Fairness and CCS.- 8.3 Weak and Strong Fairness in CCS.- 8.4 A Metric Characterization of CCS Fairness.- 8.5 Finite Delay Operators.- References.- List of Proof Rules.- Author Index.
