affirming a disjunct associativity bitwise operation boolean-valued function boolean domain boolean function commutativity contradiction disjunction elimination disjunction introduction disjunctive syllogism distributivity exclusive or first-order logic grammar grammatical conjunction javascript jevons literal logic logic gate logical nor logical biconditional logical conjunction logical connective logical graph mathematics negation or gate operator programming language proposition propositional calculus sequence point set theory sheffer stroke short-circuit evaluation truth table truth value venn diagram