Example image of eyePlorer eyePlorer map for 'Union (set theory)': Element (mathematics) Set theory Cardinality Parity (mathematics) Prime number Associativity Commutativity Empty set Identity element 0 (number) Logical disjunction Boolean algebra (structure) Complement (set theory) Intersection (set theory) Power set De Morgan's laws Distributivity Boolean ring Symmetric difference Finite set Axiom of union Existential quantification If and only if Index set Natural number Series (mathematics) Mathematical analysis Sigma-algebra Algebra of sets Borel set Chu space Composant Connected space Cover (topology) Delta-ring Disjoint union Exterior (topology) Field of sets Fσ set Hadwiger's theorem Hawaiian earring Infinity-Borel set Klee's measure problem Non-Borel set O-minimal theory Schwartz set Semialgebraic set Sigma-ring Singular measure Swiss cheese (mathematics)