Formal logic {propositional calculus, logic} {sentential calculus} can be about statements {proposition} that have one subject, one predicate, constants, and variables. Statements are propositional functions, with variable for subject and subject property for predicate. Assertion that proposition is true is a different statement than the proposition itself.
connectives
Propositional calculus uses NOT, OR, AND, IMPLIES or IF/THEN, and IF AND ONLY IF connectives. AND, NOT, and OR are constant operators.
quantifiers
Subject can have universal quantifier: for any x, subject has the property. Subject can have existential quantifier: at least one x has the property.
instantiation
Variables have possible-value sets {class, propositional calculus}. Values can substitute for subject variables {universal instantiation}. If arbitrarily selected values have a predicate property, class has property {universal generalization}. If class has property, value has property {existential instantiation}. If value has property, at least one thing in class has property {existential generalization}.
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Date Modified: 2022.0224