Definition:Universe of Discourse

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This page is about Universe in the context of Logic. For other uses, see Universe.


The universe of discourse is the term used to mean everything we are talking about.

When introducing the symbols:

$\forall$ (the universal quantifier)


$\exists$ (the existential quantifier)

it is understood that the objects referred to are those in the specified universe of discourse.

It is usual to define that universe.

Also known as

The universe of discourse is also known as:

the universe of interpretation
the domain of discourse.

Some sources use just universe or domain, but those have wider meanings.

Also see

  • Results about the universe of discourse can be found here.