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Step by Step  Building Representations in Algebraic Logic
 Journal of Symbolic Logic
, 1995
"... We consider the problem of finding and classifying representations in algebraic logic. This is approached by letting two players build a representation using a game. Homogeneous and universal representations are characterised according to the outcome of certain games. The Lyndon conditions defini ..."
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Cited by 28 (15 self)
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We consider the problem of finding and classifying representations in algebraic logic. This is approached by letting two players build a representation using a game. Homogeneous and universal representations are characterised according to the outcome of certain games. The Lyndon conditions defining representable relation algebras (for the finite case) and a similar schema for cylindric algebras are derived. Countable relation algebras with homogeneous representations are characterised by first order formulas. Equivalence games are defined, and are used to establish whether an algebra is !categorical. We have a simple proof that the perfect extension of a representable relation algebra is completely representable. An important open problem from algebraic logic is addressed by devising another twoplayer game, and using it to derive equational axiomatisations for the classes of all representable relation algebras and representable cylindric algebras. Other instances of this ap...
COMPLEXITY OF EQUATIONS VALID IN ALGEBRAS OF RELATIONS  Part II: Finite axiomatizations.
"... We study algebras whose elements are relations, and the operations are natural "manipulations" of relations. This area goes back to 140 years ago to works of De Morgan, Peirce, Schroder (who expanded the Boolean tradition with extra operators to handle algebras of binary relations). Well known exam ..."
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Cited by 17 (2 self)
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We study algebras whose elements are relations, and the operations are natural "manipulations" of relations. This area goes back to 140 years ago to works of De Morgan, Peirce, Schroder (who expanded the Boolean tradition with extra operators to handle algebras of binary relations). Well known examples of algebras of relations are the varieties RCAn of cylindric algebras of nary relations, RPEAn of polyadic equality algebras of nary relations, and RRA of binary relations with composition. We prove that any axiomatization, say E, of RCAn has to be very complex in the following sense: for every natural number k there is an equation in E containing more than k distinct variables and all the operation symbols, if 2 ! n ! !. Completely analogous statement holds for the case n !. This improves Monk's famous nonfinitizability theorem for which we give here a simple proof. We prove analogous nonfinitizability properties of the larger varieties SNrnCA n+k . We prove that the complementa...
WEAK REPRESENTATIONS OF RELATION ALGEBRAS AND RELATIONAL BASES
"... Abstract. It is known that for all finite ..."
ON CANONICITY AND COMPLETIONS OF WEAKLY REPRESENTABLE RELATION ALGEBRAS
"... Abstract. We show that the variety of weakly representable relation algebras is not canonical, nor closed under Monk completions. §1. Introduction. The aim of this paper is to show that the class wRRA of weakly representable relation algebras is not closed under taking canonical extensions, nor clos ..."
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Abstract. We show that the variety of weakly representable relation algebras is not canonical, nor closed under Monk completions. §1. Introduction. The aim of this paper is to show that the class wRRA of weakly representable relation algebras is not closed under taking canonical extensions, nor closed under taking Monk completions. We believe that the arguments used to establish this result are at least as interesting as the results themselves, and that they may add to the currently rather limited stock of useful