Predicate logic, also known as first-order logic or quantified logic, is a formal language used to express propositions in terms of predicates, variables, and quantifiers. It extends propositional logic by replacing propositional letters with a more complex notion of proposition involving predicates and quantifiers.
For example, the proposition ‘All humans are mortal’ can be expressed in predicate logic as: ∀x(Human(x) → Mortal(x))