What ∌ means
A does not contain x as an element. A set is a collection of objects, called its elements or members. If A {1, 2, 3}, then A ∌ 4 is true, because 4 is absent; A ∌ 2 is false, because 2 is present. The slash negates , meaning “contains as an element.”
“Element” matters here: ∌ does not mean “does not contain as a subset.” A subset is a set whose elements all belong to another set. With A {1, 2, 3}, {1} is a subset of A, but is not itself an element of A: the listed element is the number 1, not the set {1}. So A ∌ {1} is true.
Mathematical notation for denying membership, with the set written first.
Keep membership separate from subset inclusion.
Part of collections
Don't confuse it with
1
Related characters
1
Worth knowing
- The membership-symbol family traces back to Giuseppe Peano’s use of epsilon in 1889, linked to Latin “est” (“is”).
- Bourbaki, a group of mathematicians writing under a shared name, used a negated membership sign in 1939. This dates part of the notation’s history, not necessarily the exact glyph ∌.
More like this
10
How to type or find ∌
- Search it as
- ∌ meaning · does not contain symbol · not a member · ∌ vs ∉ · A ∌ x
- Shows up in
- Anything that takes text · its shape is whatever your font draws
∌\220CCodes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.