ThmDex – An index of mathematical definitions, results, and conjectures.
▼ Set of symbols
▼ Propositional connective
▼ Set of propositional connectives
▼ Complete set of propositional connectives
▼ Set of propositional symbols
▼ Set of predicate symbols
▼ Set-theoretic alphabet
▼ Set-theoretic language
▼ Set-theoretic expression
▼ Set-theoretic formula
▼ Class term
Definition D13
Empty set
Children
▶ Nonempty set
Results
▶ Empty set is subset of every set