Logic Rules of Inference
The truth table rules outline how the truth values of logical expressions are determined based on the truth values of their individual components (propositional variables and logical operators). Here are the fundamental truth table rules for some common logical operators:
1. Conjunction (∧):
- T ∧ T = T
- T ∧ F = F
- F ∧ T = F
- F ∧ F = F
2. Disjunction (∨):
- T ∨ T = T
- T ∨ F = T
- F ∨ T = T
- F ∨ F = F
3. Negation (¬):
- ¬T = F
- ¬F = T
4. Implication (⇒):
- T ⇒ T = T
- T ⇒ F = F
- F ⇒ T = T
- F ⇒ F = T
5. Biconditional (⇔):
- T ⇔ T = T
- T ⇔ F = F
- F ⇔ T = F
- F ⇔ F = T
These rules form the basis for constructing truth tables and evaluating the truth values of complex logical expressions. To determine the truth value of an expression, follow the truth table rules for the respective logical operators and apply them to the truth values of the propositional variables in the expression.
When constructing a truth table for an expression with multiple propositional variables and operators, combine the truth values of the variables and operators step-by-step, following the rules above until you reach the final truth value for the entire expression. This process allows you to systematically evaluate the truth values and determine whether the expression is true (T) or false (F) for all possible combinations of truth values for the variables involved.