About the Book
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 59. Chapters: Logical conjunction, Logical disjunction, Entailment, Exclusive or, Sheffer stroke, Contradiction, Negation, Propositional formula, Truth table, Converse nonimplication, Tautology, List of logic systems, Functional completeness, Logical biconditional, Material conditional, Implicational propositional calculus, Rule of inference, Intermediate logic, Logical NOR, Contingency, Open sentence, Frege system, Strict conditional, System L, Clause, Wolfram axiom, Syncategorematic term, Zeroth-order logic, Substitution, Formation rule, Absorption law, Unsatisfiable core, Propositional variable, Material nonimplication, Literal, Converse implication, Negation normal form, Principle of distributivity, Nicod's axiom, Second-order propositional logic, Probabilistic proposition. Excerpt: In propositional logic, a propositional formula is a type of syntactic formula which is well formed and has a truth value. If the values of all variables in a propositional formula are given, it determines a unique truth value. A propositional formula may also be called a propositional expression, a sentence, or a sentential formula. A propositional formula is constructed from simple propositions, such as "x is greater than three" or propositional variables such as P and Q, using connectives such as NOT, AND, OR, and IMPLIES; for example: (x = 2 AND y = 4) IMPLIES x + y = 6.In mathematics, a propositional formula is often more briefly referred to as a "proposition," but, more precisely, a propositional formula is not a proposition but a formal expression that denotes a proposition, a formal object under discussion, just like an expression such as "" is not a value, but denotes a value. In some contexts, maintaining the distinction may be of importance. For the purposes of the propositional calculus, propositions (utterances, sentences, assertions)...
