Truth Table Rules
1. Let's start by stating the problem: We want to understand the rules for constructing truth tables in logic.
2. A truth table is a tool used in logic to determine the truth value of a compound statement based on the truth values of its components.
3. The basic truth values are True (T) and False (F).
4. For a statement with $n$ variables, the truth table has $2^n$ rows, representing all possible combinations of truth values.
5. Common logical operators and their truth table rules:
- **Negation (NOT, \neg)**: flips the truth value.
$$\neg T = F, \quad \neg F = T$$
- **Conjunction (AND, \wedge)**: true only if both operands are true.
$$T \wedge T = T, \quad T \wedge F = F, \quad F \wedge T = F, \quad F \wedge F = F$$
- **Disjunction (OR, \vee)**: true if at least one operand is true.
$$T \vee T = T, \quad T \vee F = T, \quad F \vee T = T, \quad F \vee F = F$$
- **Implication (IF...THEN, \to)**: false only if the first is true and the second is false.
$$T \to T = T, \quad T \to F = F, \quad F \to T = T, \quad F \to F = T$$
- **Biconditional (IF AND ONLY IF, \leftrightarrow)**: true if both operands have the same truth value.
$$T \leftrightarrow T = T, \quad T \leftrightarrow F = F, \quad F \leftrightarrow T = F, \quad F \leftrightarrow F = T$$
6. To build a truth table:
- List all variables.
- Write all possible combinations of truth values.
- Apply the operator rules step-by-step to find the truth value of the compound statement.
7. Example: For $p \wedge \neg q$, with variables $p$ and $q$:
- List all combinations: $(T,T), (T,F), (F,T), (F,F)$.
- Compute $\neg q$ for each.
- Compute $p \wedge \neg q$ using the conjunction rule.
This systematic approach helps analyze logical statements clearly and accurately.