ISO 31-11 - Mathematical Logic

Mathematical Logic

Sign Example Name Meaning and verbal equivalent Remarks
∧ p ∧ q conjunction sign p and q
∨ p ∨ q disjunction sign p or q (or both)
¬ ¬ p negation sign negation of p; not p; non p
⇒ p ⇒ q implication sign if p then q; p implies q Can also be written as q ⇐ p. Sometimes → is used.
∀ ∀x∈A p(x)
(∀x∈A) p(x)		 universal quantifier for every x belonging to A, the proposition p(x) is true The "∈A" can be dropped where A is clear from context.
∃ ∃x∈A p(x)
(∃x∈A) p(x)		 existential quantifier there exists an x belonging to A for which the proposition p(x) is true The "∈A" can be dropped where A is clear from context.
∃! is used where exactly one x exists for which p(x) is true.

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