In mathematical logic, the spectrum of a sentence is the set of natural numbers occurring as the size of a finite model in which a given sentence is true. By a result in descriptive complexity, a set of natural numbers is a spectrum if and only if it can be recognized in non-deterministic "weak" exponential time (2^{O(n)}), which is a subclass of NEXP. == Definition == Let ψ be a sentence in first-order logic.
In mathematical logic, the spectrum of a sentence is the set of natural numbers occurring as the size of a finite model in which a given sentence is true. By a result in descriptive complexity, a set of natural numbers is a spectrum if and only if it can be recognized in non-deterministic "weak" exponential time (2^{O(n)}), which is a subclass of NEXP. == Definition == Let ψ be a sentence in first-order logic.
Source: Wikipedia "Spectrum of a sentence" · CC BY-SA 4.0
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