Editing Logical disjunction (section)

==Set theory==
{{Expand section|date=February 2021}}
The [[Element (mathematics)|membership]] of an element of a [[union (set theory)|union set]] in [[set theory]] is defined in terms of a logical disjunction: <math>x\in A\cup B\Leftrightarrow (x\in A)\vee(x\in B)</math>. Because of this, logical disjunction satisfies many of the same identities as set-theoretic union, such as [[associativity]], [[commutativity]], [[distributivity]], and [[de Morgan's laws]], identifying [[logical conjunction]] with [[set intersection]], [[logical negation]] with [[set complement]].<ref>{{cite book |last1=Ebbinghaus |first1=Heinz-Dieter |title=Einführung in die Mengenlehre |date=2021 |publisher=Springer |isbn=978-3-662-63865-1 |page=32 |edition=5 |language=German}}</ref>