Not symbol (¬)
¬ means “not” in logic. ¬p, read “not p”, is the negation of p: it is true when p is false and false when p is true.
Easily confused with
How to read it
Oscar Levin’s Discrete Mathematics reads ¬P as “not P”, a negation, and says it is true when P is false. Negating twice gets back to where you started: OpenStax’s Contemporary Mathematics writes the negation of not p as p. The sign goes in front of the statement it negates. Unicode names the character NOT SIGN (U+00AC); in typography, its chart notes, the same mark is called an angled dash.
Also searched as: ¬, hook symbol, ~ in logic, logical not, negation symbol, not sign.
¬ or ~
Both are current. forall x: Calgary calls ¬ the hoe and ~ the swung dash or tilde, and gives both as common symbols for negation; OpenStax’s Contemporary Mathematics uses the tilde, writing not p as ~p. forall x adds that older texts sometimes negated a formula with a line over it, or with a minus sign. In some advanced systems the two signs mean two different kinds of negation, but in an introductory course they are the same thing. The keyboard tilde ~ has other jobs outside logic.
Look-alikes
Unicode cross-refers ¬ to two characters that look like it turned round: the reversed not sign ⌐ (U+2310) and the turned not sign ⌙ (U+2319). In electronics, “not” is drawn as the NOT gate, a triangle with a small circle.
Read next
- Next in Logic symbolsImplies symbol (→)→ means “implies” or “if … then” in logic. p → q, read “if p then q”, is a conditional: it is false only when p is true and q is false.
- The NOT gate is the circuit form of logical “not”.NOT gate (inverter)A NOT gate, or inverter, outputs the opposite of its input: 1 becomes 0 and 0 becomes 1. Its symbol is a triangle with a small circle at its tip.
More logic symbols
The same shape elsewhere
Browse symbols drawn with lines.
Sources
- Contemporary Mathematics, 2.1 Statements and Quantifiers, OpenStax (Rice University), Negating logical statements symbolically
- forall x: Calgary. An Introduction to Formal Logic, P. D. Magnus, Tim Button, Robert Trueman and Richard Zach, forall x: Calgary (Fall 2025 edition), Open Logic Project, University of Calgary, Sec. 5.1 Negation; Appendix A.2 Alternative symbols
- Discrete Mathematics, 0.2 Mathematical Statements, Oscar Levin, Discrete Mathematics: An Open Introduction, 3rd edition, Oscar Levin, University of Northern Colorado (Open Math Books), Logical connectives
- Earliest Uses of Symbols of Set Theory and Logic, Jeff Miller, Earliest Uses of Various Mathematical Symbols, MacTutor History of Mathematics, University of St Andrews, Negation
- Latin-1 Supplement: Range 0080–00FF (code chart), The Unicode Standard, Version 18.0, Unicode Consortium, Latin-1 punctuation and symbols, 00AC
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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