Definition:Unsatisfiable/Boolean Interpretations
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Definition
Let $\mathbf A$ be a WFF of propositional logic.
$\mathbf A$ is called unsatisfiable (for boolean interpretations) if and only if:
- $\map v {\mathbf A} = \F$
for every boolean interpretation $v$ for $\mathbf A$.
In terms of validity, this can be rendered:
- $v \not \models_{\mathrm {BI} } \mathbf A$
that is, $\mathbf A$ is invalid in every boolean interpretation of $\mathbf A$.
Also known as
Unsatisfiable formulae are more commonly referred to as contradictions.
To avoid ambiguity with inconsistent formulae, the latter term is discouraged on $\mathsf{Pr} \infty \mathsf{fWiki}$ when specifically referring to unsatisfiability.
Also see
- Definition:Valid (Boolean Interpretation)
- Definition:Tautology (Boolean Interpretations)
- Definition:Satisfiable (Boolean Interpretations)
- Results about contradictions can be found here.
Sources
- 1959: A.H. Basson and D.J. O'Connor: Introduction to Symbolic Logic (3rd ed.) ... (previous) ... (next): $\S 3.5$: The Classification of Propositions
- 1965: E.J. Lemmon: Beginning Logic ... (previous) ... (next): Chapter $2$: The Propositional Calculus $2$: $3$ Truth-Tables
- 1988: Alan G. Hamilton: Logic for Mathematicians (2nd ed.) ... (previous) ... (next): $\S 1$: Informal statement calculus: $\S 1.2$: Truth functions and truth tables: Definition $1.5 \ \text{(b)}$
- 2012: M. Ben-Ari: Mathematical Logic for Computer Science (3rd ed.) ... (previous) ... (next): $\S 2.5$: Definition $2.38$