(*) A Syllogistic Solitaire

Abstract

In the very prototypical form in which they were originally conceived, some of the decision algorithms for set contexts proceed by blind search. They do this so exhaustively over a large space as to baffle any implementation attempt aimed at efficiency. One would at least expect clarity to be a reward to low efficiency; but such decision algorithms often are somewhat hard to understand and even harder to extend with the treatment of settheoretical constructs that were not built into them from the outset. In this chapter, we re-examine one of them, with two goals in mind: one is to make a tough decidability result easier to understand, another is to bring it closer to extensions some of which have been attained only recently.