Definition:Classes of WFFs/Sentence
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Definition
Let $\LL_1$ be the language of predicate logic.
A WFF is said to be a sentence if and only if it contains no free variables.
To denote particular classes of sentences, $\map {SENT} {\PP, \FF, \KK}$ and analogues may be used, similar to the notation for classes of WFFs.
Sources
- 1996: H. Jerome Keisler and Joel Robbin: Mathematical Logic and Computability: $\S 2.3$
- 2009: Kenneth Kunen: The Foundations of Mathematics ... (previous) ... (next): $\text{II}.5$ First-Order Logic Syntax: Definition $\text{II}.5.5$