Logic: The Big Picture Propositional logic: atomic statements are facts –Inference via resolution is sound and complete (though likely computationally intractable) First-order logic: adds variables, relations, and quantification –Inference is essentially a generalization of propositional inference –Resolution is still sound and complete, but not guaranteed to terminate on non-entailed sentences (semidecidable) –Simple inference procedures (forward chaining and backward chanining) available for knowledge bases consisting of definite clauses
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