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Notation and terminology

Intersection is written using the symbol "${\displaystyle \cap }$" between the terms; that is, in infix notation. For example: $${\displaystyle \{1,2,3\}\cap \{2,3,4\}=\{2,3\}}$$$${\displaystyle \{1,2,3\}\cap \{4,5,6\}=\varnothing }$$$${\displaystyle \mathbb {Z} \cap \mathbb {N} =\mathbb {N} }$$$${\displaystyle \{x\in \mathbb {R} :x^{2}=1\}\cap \mathbb {N} =\{1\}}$$ The intersection of more than two sets (generalized intersection) can be written as: $${\displaystyle \bigcap _{i=1}^{n}A_{i}}$$ which is similar to capital-sigma notation.