U2229

U+2229 is the Unicode code point for the N-ary Intersection symbol ∩. It is used to denote the intersection of a family of sets in mathematical notation. In set theory and related fields, the intersection of a collection {A_i | i ∈ I} is written as ∩_{i∈I} A_i, while binary intersections are written simply as A ∩ B. The term “N-ary” reflects the symbol’s ability to represent intersections over any indexed collection, not just two sets.

In mathematical practice, the intersection operator is commutative and associative, and it interacts with other set operations through standard laws such as distributivity over unions and De Morgan’s laws for complements. The symbol also appears in logic and lattice theory as a representation of the meet operation in certain lattices, corresponding to logical conjunction in set-theoretic terms.

Encoding and typography: U+2229 resides in the Unicode Mathematical Operators block. Its appearance depends on the chosen font, and common TeX/LaTeX usage represents the same idea with \cap or \bigcap for larger intersections. In HTML and other formats, the symbol can be rendered as the character entity or by directly using the character, provided the font supports it.

Overall, U+2229 serves as the standard, language-agnostic symbol for intersection in mathematical writing, compactly conveying the common operation of finding elements common to all sets in a collection.