Reconstructing a single-head formula to facilitate logical forgetting

12/18/2020

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by   Paolo Liberatore, et al.

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Logical forgetting may take exponential time in general, but it does not when its input is a single-head propositional definite Horn formula. Single-head means that no variable is the head of multiple clauses. An algorithm to make a formula single-head if possible is shown. It improves over a previous one by being complete: it always finds a single-head formula equivalent to the given one if any.