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In the process algebra community it is sometimes suggested that, on somelevel of abstraction, any distributed system can be modelled in standardprocess-algebraic specification formalisms like CCS. This sentiment isstrengthened by results testifying that CCS, like many similar formalisms, isTuring powerful and provides a mechanism for interaction. This paper countersthat sentiment by presenting a simple fair scheduler---one that in suitablevariations occurs in many distributed systems---of which no implementation canbe expressed in CCS, unless CCS is enriched with a fairness assumption.  Since Dekker's and Peterson's mutual exclusion protocols implement fairschedulers, it follows that these protocols cannot be rendered correctly in CCSwithout imposing a fairness assumption. Peterson expressed this algorithmcorrectly in pseudocode without resorting to a fairness assumption, so itfurthermore follows that CCS lacks the expressive power to accurately capturesuch pseudocode.

CCS: It's not Fair! Fair Schedulers cannot be implemented in CCS-like languages even under progress and certain fairness assumptions