Relationship between two propositional forms P and Q, noted as “P ↔ Q” or “P is equal to Q”, which is true when P and Q both simultaneously have the same truth value and false in other cases.
Synonym for biconditional propositional form.
The biconditional truth table is:
| P | Q | P ↔ Q |
| T | T | T |
| T | F | F |
| F | T | F |
| F | F | T |
Example
An equation is a propositional form.
2x + 8y = 16 ↔ x + 4y = 8
This expression is a biconditional propositional form that can also be translated by: we can multiply or divide all the terms in an equation by a non-zero number without changing its truth value..