# extensionality

*Philosophy dictionary.
Academic.
2011.*

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**Extensionality**— In logic, extensionality refers to principles that judge objects to be equal if they have the same external properties. It is the opposite concept of intensionality, which is concerned with whether two descriptions are intended to be the same or… … Wikipedia**extensionality**— noun see extensional … New Collegiate Dictionary**extensionality**— noun a) The principle that objects are equal if and only if their observed properties are the same, regardless of internal processes that lead to those properties. b) The principle that functions are equal if and only if they operate on the same… … Wiktionary**extensionality**— ex·ten·sion·al·i·ty … English syllables**extensionality**— ikˌstenchəˈnaləd.ē, (ˌ)ekˌ noun ( es) : the quality or state of being extensional … Useful english dictionary**extensionality, axiom of**— Basic axiom of set theory . It asserts that sets are identical if and only if they have the same members … Philosophy dictionary**Axiom of extensionality**— In axiomatic set theory and the branches of logic, mathematics, and computer science that use it, the axiom of extensionality, or axiom of extension, is one of the axioms of Zermelo Fraenkel set theory. Formal statement In the formal language of… … Wikipedia**axiom of extensionality**— noun One of the axioms in axiomatic set theory, equivalent to the statement that two sets are equal if and only if they contain the same elements … Wiktionary**extension**— extensionality, extensionalism, n. extensional, adj. extensionally, adv. extensionless, adj. /ik sten sheuhn/, n. 1. an act or instance of extending. 2. the state of being extended. 3. that by which something is extended; an addition: a four room … Universalium**Mereology**— In philosophy and mathematical logic, mereology (from the Greek μέρος, root: μερε(σ) , part and the suffix logy study, discussion, science ) treats parts and the wholes they form. Whereas set theory is founded on the membership relation between a … Wikipedia