WordNet (r) 3.0 (2006):

propositional calculus
    n 1: a branch of symbolic logic dealing with propositions as
         units and with their combinations and the connectives that
         relate them [syn: propositional logic, propositional
         calculus]

The Free On-line Dictionary of Computing (30 December 2018):

propositional logic
propositional calculus

    (or "propositional calculus") A system of symbolic
   logic using symbols to stand for whole propositions and
   logical connectives.  Propositional logic only considers
   whether a proposition is true or false.  In contrast to
   predicate logic, it does not consider the internal structure
   of propositions.

   (2002-05-21)