Concepts
- proposition
- premise and conclusion
- logical fallacies
- argument
- well-formed formula
Languages
- propositional logic
- “If it is raining and cold, then the ground is wet”
- predicate logic (first-order logic)
- “IF x is a parent of y, then x is older than y”
- higher-order logic
Proof Systems
See formal system, proof system
Concepts
Proof Methods
- truth table
- truth tree (semantic tableau)
- direct proofs
- natural deduction
Logical Properties
For A Single Formula
- validity
- satisfiable
- contradiction/logical falsehood/unsatisfiable
For Two Formulas
For A Set of Formulas
- (jointly) satisfiable/unsatisfiable
- logical consistency
- contradictory
- contraries