  The usual modelling of the syllogisms of the Organon by a calculus of classes
does not include relations. Aristotle may however have envisioned them in the
first two books as the category of relatives, where he allowed them to compose
with themselves. Composition is the main operation in combinatory logic, which
therefore offers itself for a new kind of modelling. The resulting calculus
includes also composition of predicates by logical connectives.
