Predicate
A predicate is a logical expression. In the context of set theory, usually a predicate is a statement which can be expressed using only symbols from symbolic logic, variables, and the set-theoretic relations and . Additional relations can be made with predicates by using propositional logic quantifiers such as and , which mean "for-all" and "there exists" respectively.
Examples
In English, this predicate reads, "The empty set is an element of ." Note that this is not true for all sets.
In English, this translates to, "For all sets , the empty set is a subset of ." Since is an abbreviation for the predicate , this can be rewritten using only logical symbols, variables, and the set-theoretic notations and , as follows:
- .
In English, this revised predicate reads, "For all sets , for all sets , if is an element of the empty set, then is an element of ."
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