LOGIC MAIN PAGE

LOGICAL OPERATORS

Sample sentences
AND operator
IF/THEN operator
NOT operator
OR operator
XOR operator

RULES OF LOGIC

Chain Rule
Contrapositive
DeMorgan's Law
Disjunctive Inference
Disjunctive Infer. (XOR)
Double Negation
Modus Ponens
Modus Tollens
Mutual Exclusion
Simplification

VALIDITY PROOFS

2-step
3-step
4-step
5-step or more

LOGIC

This section of the site will help you get acquainted with formal logic. There are three main categories shown in light blue on the left navigation bar:

Logical Operators

These are the major building blocks of logic. The knowledge of the five operators and their truth tables is essential for understanding most logic problems and their solutions. There are links to the rules of logic pertinent to a specific operator.

Rules of Logic

Each logical operator has a set of rules associated with it. This category explores all the logic rules you will need to apply in order to solve validity proof problems. For each rule, there are links to relevant problems.

Validity Proofs

This section contains actual validity proof problems involving Logical Operators and Rules of Logic, and solutions with full explanations.