Fairness and Hyperfairness

In 1993, Attie, Francez, and Grumberg published a paper titled Fairness and Hyperfairness in Multi-Party Interactions. This was a follow-up to the 1988 paper Appraising Fairness in Languages for Distributed Programming by Apt, Francez, and Katz, which attempted to define fairness. I have long believed that the only sensible formal definition of fairness is machine closure, which is essentially one of the conditions mentioned by Apt, Francez, and Katz. (They called it feasibility and phrased it as a condition on a language rather than on an individual specification.) I refereed the Attie, Francez, and Grumberg paper and found it rather uninteresting because it seemed to be completely language-dependent. They apparently belonged to the school, popular in the late 70s and early 80s, that equated concurrency with the CSP programming constructs. I wrote a rather unkind review of that paper, which obviously didn’t prevent its publication. Years later, it suddenly struck me that there was a language-independent definition of hyperfairness–or more precisely, a language-independent notion that seemed to coincide with their definition on a certain class of CSP programs. I published this paper for three reasons: to explain the new definition of hyperfairness; to explain once again that fairness is machine closure and put to rest the other two fairness criteria conditions of Apt, Francez, and Katz; and, in some small way, to make up for my unkind review of the Attie, Francez, and Grumberg paper.