Definition:Closed Statement
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Definition
Let $P$ be a statement.
$P$ is a closed statement if and only if $P$ contains only bound occurrences of any variables that may appear in it.
That is, such that it contains no free occurrences of variables.
Examples
True Statement
The statement:
- $\exists x \in \Z: x^2 + 2 = 11$
is a closed statement that is true, as it is satisfied by the integers $x = 3$ and $x = -3$.
False Statement
The statement:
- $\exists x \in \R: x^2 = -1$
is a closed statement that is false, as it is satisfied by no real number $x$.
Also see
Sources
- 1972: A.G. Howson: A Handbook of Terms used in Algebra and Analysis ... (previous) ... (next): $\S 1$: Some mathematical language: Variables and quantifiers
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): variable: 2.
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): variable: 2.