Query Q If we want to know whether K => Q i.e. not K or Q is True i.e. K and not Q is False In other words K augmented with Resolution procidor may bot actual finish. Resolution may never end; never (whatever algorithm): undecidability Other resolution may take an huge time to be solved: intractability. Propositional logic is decidbale, but intractable (SAT, NP ..). Automates reasoning, semantic-web. OWL-DL, OWL-lite (description logic: leader sets person ...) deci Statements about the structure of the world are not undecibebality but may intractability, Horn logic is essential rules, like a person if there is only one conclusions on the right statement. Such statements are undecidable (except with caveats); but always tractable. Tags: Edit this page |
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