First-order logic - Wikipedia
https://en.wikipedia.org/wiki/First-order_logicThere are many variations of first-order logic. Some of these are inessential in the sense that they merely change notation without affecting the semantics. Others change the expressive power more significantly, by extending the semantics through additional quantifiers or other new logical symbols. For example, infinitary logics permit formulas of infinite size, and modal logics add symbols for possibility and necessity.
First-Order Logic - Syntax, Semantics, Resolution
www.cs.yale.edu › homes › piskacSyntax From a Signature to Formulas General First-Order Formulas FΣ(X) is the set of first-order formulas over Σ defined as follows: F,G,H ::= ⊥ (falsum) | ⊤ (verum) | A (atomic formula) | ¬F (negation) | (F ∧G) (conjunction) | (F ∨G) (disjunction) | (F =⇒ G) (implication) | (F ≡ G) (equivalence) | ∀xF (universal quantification)
First Order Logic
courses.engr.illinois.edu › FirstOrderLogicdistiguishing features of rst order logic is the use of quanti ers, that allow one to state whether something holds for some or all individuals. 1 Syntax First order logic formulas are de ned over a vocabulary or signature that identi es the predicates and constants that can be used in the formulas. De nition 1.