universe of discourse

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universe of discourse

In ontology, the set of all entities that can be represented in some declarative language or other formal system.

Each entity is represented by a name and may have some human-readable description of its meaning. Formal axioms constrain the interpretation and well-formed use of these names.

Universe of Discourse


a class (set) of objects considered within a given context. A context here is understood to mean a distinct discourse or a sentence expressing a distinct discourse, a collection of sentences, a fragment of a scientific theory, or an entire theory. In number theory, the universe of discourse in the natural-number series (the set of nonnegative integers); in mathematical analysis, the set of real numbers; in botany, the set of all plants (more precisely, the set of all plant species); and in the predicate calculus or logic of classes, any fixed nonempty domain. The universe of discourse is also referred to as the universal set, the opposite in logic and set theory of what is known as the empty set; the empty set contains no object of a given type and is the complement of the universal set.

The generally accepted idea of a universe of discourse as a given domain of objects was proposed by J. Venn. In number theory, according to this definition, the complement of the set of even numbers is the set of odd numbers and not the “set of all conceivable objects, none of which is an even number”— which would include, for example, this encyclopedia and everything in the world other than the even numbers. This definition has replaced G. Frege’s concept of a “universal” universe of discourse, which had led to paradoxes.

References in periodicals archive ?
It looks backward to an entity or situation that has already been present in the universe of discourse, in a way similar to the normal anaphoric reference.
It may well be that the referent of 'the man' appears for the first time in the universe of discourse.
Its core function is to indicate that the referent, or more precisely the mental representation of the referent in the universe of discourse, that it is used with is to be interpreted as an entity that the addressee can identify from among the other members of the class in the context.
Or, in terms of Boole's logical algebra, V + (1 - V) = 1, where 1 represents the universe of discourse and (1 - v) stands for not-V.
Normal fuzzy set: A fuzzy set A of the universe of discourse X is called a normal fuzzy set implying that there exist at least one x [member of] X such that [[mu].
This universe of discourse was put to work debating the issues of the day of which the most important was that raised by the conquista itself, and is reflected in the Gran Requisitorio in which diverse views were thrashed out to the edification of all and the satisfaction of few if any.
Both categories of appeal acknowledge a universe of discourse defined by language in action, language whose reference is always shared by (and distributed among) a world of various speakers and various speakings.