nly such an expression) can appear in the 0th (or arg0 ) position (i.e. as the term immediately following the opening parenthesis) of a #$CycLSentence. The name `TruthFunction' derives in part from the fact that the sentences thus formed (if semantically well-formed and quantificationally closed; see #$CycLSentence-Assertible and #$CycLClosedSentence) are the kind of expression that can be true or false (with respect to a given context and interpretation). Though not really functions (cf. #$Function-Denotat