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In high school and college math courses, we learn about ways to express groups of items as subsets and supersets. This branch of mathematics is called set theory. The expression, X ∈ A means “Item X exists in set A”, or “X is an element of set A”. The symbol looks like an E,…
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Set Theory In high school and college math courses, we learn about ways to express groups of items as subsets and supersets. This branch of mathematics is called set theory. The expression, X ∈ A means “Item X exists in set A”, or “X is an element of set A”. The symbol looks like…