Formulas
Examples
| Symbol | ASCII | Unicode |
|---|---|---|
| Negation | ~ or - | ¬ |
| Conjunction | & or /\ | ∧ |
| Disjunction | | or \/ | ∨ |
| Conditional | -> or => | → |
| Biconditional | <-> or <=> | ↔ |
| Universal | Ax or Vx | ∀x |
| Existential | Ex | ∃x |
| Identity | a=b | a=b |
Ax Ay Pxy — Every x stands in P to every yEx(Px & Qx) — Something is both P and Q~ExPx — Nothing is PAx Ay (Rxy -> Ryx) — R is symmetric∀x∃y Rxy — Everything bears R to somethingPa & Qb — a is P and b is Qa=b -> (Pa -> Pb) — Leibniz law instanceEx(Px & Ay(Py -> y=x)) — There is exactly one PConstants: a, b, c, d, e | Variables: x, y, z | Predicates: P, Q, R, S, T
Atomic formulas use juxtaposition: Pxy, Rxa, Qab — no parentheses or commas between arguments.