Set

:This article is about sets in mathematics. For other senses, see set (disambiguation).

Intersections

A new set can also be constructed by determining which members two sets have "in common". The intersection of A and B, denoted by A ∩ B, is the set of all things which are members of both A and B. If A ∩ B  =  ø, then A and B are said to be disjoint.

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The intersection of A and B

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Examples:

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:*{1, 2} ∩ {red, white} = ø

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:*{1, 2, green} ∩ {red, white, green} = {green}

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:*{1, 2} ∩ {1, 2} = {1, 2}

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Some basic properties of intersections:

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:*A ∩ B   =   B ∩ A

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:*A ∩ B  is a subset of  A

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:*A ∩ A   =   A

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:*A ∩ ø   =   ø

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For more information about intersections of sets, see Intersection (set theory).

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