| Validity, Satisfiability, Models |
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| • | A
sentence is valid if it is true for all |
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| possible
truth assignments (a.k.a. a |
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| tautology)
e.g. (P ÚØP) |
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| • | A
sentence is satisfiable if there exists a |
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| “satisfying”
truth assignment (i.e. a truth |
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| assignment
for which the sentence is true). |
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| • | A
truth assignment which satisfies a |
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| sentence
is a model of that sentence. |
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