2.1 Statements

Logic

Introduction

• logic is a process of deducing information correctly, not just deducing correct information.

Statements

• a statement is a sentence or a mathematical expression that is either definitely true or definitely false.
  • E.g. If a circle has radius r, then its area is πr 2 square units. ⇒ True
  • E.g. All right triangles are isosceles. ⇒ False
• Statements can be expressed as letters
  • E.g. $P$ : For every integer $n$ > 1, the number $2n$ −1 is prime

Open Sentences

• a sentence whose truth depends on the value of one or more variables, is called an open sentence
  • E.g. $R(f,g)$ : The function $f$ is the derivative of the function $g$.