# COMPSCI 70 Chapter Notes - Chapter 1: Propositional Calculus, Contraposition, Logical Equivalence

## Document Summary

Propositional logic propositional logic - a language that treats statements as either true or false (black or white) (no grey) The first step to propositional logic is to state a proposition. Propositional logic is the joining and/or modifying of entire propositions or statements to form more complicated propositions or statements. Statements refer to the entire statement (they can include implications, sub -propositions, etc. ) How to create a propositional logic statement (2 ways) can be a simple, single proposition or a complex proposition (one that is has a series of propositions combined with connectives) (~predicate~) can be an implication statement. If (~predicate~) is an implication statement, then it does not include the (~quantifier~) part in the implication. Law of the excluded middle: value of a proposition is true or false (cannot be anything in between) Connectives are used to create different proposition forms (propositions can come in various structures and forms) tautology - a statement that is always true.