Complexity of equational theory of relational algebras with standard projection elements
نویسندگان
چکیده
منابع مشابه
Complexity of equational theory of relational algebras with standard projection elements
The class TPA of true pairing algebras is defined to be the class of relation algebras expanded with concrete set theoretical projection functions. The main results of the present paper is that neither the equational theory of TPA nor the first order theory of TPA are decidable. Moreover, we show that the set of all equations valid in TPA is exactly on the Π11 level. We consider the class TPA o...
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In connection with a problem of L. Henkin and J.D. Monk we show that the variety generated by TPA’s – relation algebras (RA’s) expanded with concrete set theoretical projection functions – and the first–order theory of the class TPA are not axiomatizable by any decidable set of axioms. Indeed, we show that Eq(TPA) – all equations valid in TPA – is exactly on the Π1 level. The same applies if we...
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ژورنال
عنوان ژورنال: Synthese
سال: 2015
ISSN: 0039-7857,1573-0964
DOI: 10.1007/s11229-015-0689-1