Negation Elimination in Empty or Permutative Theories
نویسندگان
چکیده
منابع مشابه
Unification in Permutative Equational Theories is Undecidable
An equational theory E is permutative if for all terms s, t : s =E t implies that the terms s and t contain the same symbols with the same number of occurrences. The class of permutative equational theories includes the theory of AC (associativity and commutativity). It is shown in this research note that there is no algorithm that decides E-unifiability of terms for all permutative theories. T...
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It has been proposed in [1] to perform deduction modulo leaf permutative theories, which are notoriously hard to handle directly in equational theorem proving. But unification modulo such theories is a difficult task, not tackled in [1]; a subclass of flat equations has been considered only recently, in [2]. Our emphasis on group theoretic structures led us in [6] to the definition of a more ge...
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In the modal μ-calculus, a formula is well-formed if each recursive variable occurs underneath an even number of negations. By means of De Morgan’s laws, it is easy to transform any well-formed formula φ into an equivalent formula without negations – the negation normal form of φ . Moreover, if φ is of size n, the negation normal form of φ is of the same size O(n). The full modal μ-calculus and...
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This article answers two questions (posed in the literature), each concerning the guaranteed existence of proofs free of double negation. A proof is free of double negation if none of its deduced steps contains a term of the form n(n(t)) for some term t, where n denotes negation. The first question asks for conditions on the hypotheses that, if satisfied, guarantee the existence of a double-neg...
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ژورنال
عنوان ژورنال: Journal of Symbolic Computation
سال: 1998
ISSN: 0747-7171
DOI: 10.1006/jsco.1998.0203