Publications (16)1.07 Total impact
 Theor. Comput. Sci. 01/1984; 28:4581.
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ABSTRACT: This paper is concerned mainly with classes (categories) of ordered algebras which in some signature are axiomatizable by a set of inequations between terms (‘varieties’ of ordered algebras) and also classes which are axiomatizable by implications between inequations (‘quasi varieties’ of ordered algebras). For example, if the signature contains a binary operation symbol (for the monoid operation) and a constant symbol (for the identity) the class of ordered monoids M can be axiomatized by a set of inequations (i.e. expressions of the form t≤t'. However, if the signature contains only the binary operation symbol, the same class M cannot be so axiomatized (since it is not now closed under subalgebras). Thus, there is a need to find structural, signature independent conditions on a class of ordered algebras which are necessary and sufficient to guarantee the existence of a signature in which the class is axiomatizable by a set of inequations (between terms in this signature). In this paper such conditions are found by utilizing the notion of ‘Pcategories’. A Pcategory C is a category such that each ‘Homset’ C(a,b) is equipped with a distiguished partial order which is preserved by composition. Aside from proving the characterization theorem, it is also the purpose of the paper to begin the investigation of Pcategories.Journal of Pure and Applied Algebra 07/1983; 29(1):13–58. · 0.53 Impact Factor  [show abstract] [hide abstract]
ABSTRACT: The purpose of this paper is twofold: first to show how a natural mathematical formulation of the “solution” of a system of recursion equations is formally almost identical with wellknown formulations of a solution of a system of “iteration equations.” The second aim is to present a construction which takes an algebraic theory T and yields another algebraic theory M(T) whose morphisms correspond to systems of recursion equations over T. This construction is highly uniform, i.e., the correspondence between T and M(T) is functorial.Journal of Computer and System Sciences. 01/1983; 
Article: Finitary quasivarieties
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ABSTRACT: A pair (,U) consisting of a category with coequalizers and a functor U: → Set is a weak quasivariety if U has a left adjoint and U preserves and reflects regular epis. It is known that every weak quasivariety is equivalent to a concrete quasivariety, i.e. a category of Σalgebras which has all free algebras and which is closed with respect to products and subalgebras. It is also known that if U preserves monic direct limits, is equivalent to a concrete quasivariety of Σalgebras in which Σ contains no function symbols of infinite rank; and if U preserves all direct limits, is equivalent to a concrete quasivariety of Σalgebras definable by a set of implications of the form where ti and si are Σterms and m is a nonnegative integer. This paper concerns several definitions of ‘finiteness’ in a category theoretic setting and some theorems on weak quasivarieties. Two main theorems characterize those weak quasivarieties (, U) such that U preserves all direct limits.Journal of Pure and Applied Algebra 08/1982; 25(2):121–154. · 0.53 Impact Factor  ACM Trans. Program. Lang. Syst. 01/1982; 4:711732.

Conference Proceeding: Parameter Passing in Algebraic Specification Languages.
Program Specification, Proceedings of a Workshop, Aarhus, Denmark, August 1981; 01/1981  Theor. Comput. Sci. 01/1981; 15:223249.
 SIAM J. Comput. 01/1980; 9:2545.
 SIAM J. Comput. 01/1980; 9:525540.

Conference Proceeding: More on advice on structuring compilers and proving them correct.
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ABSTRACT: Without AbstractSemanticsDirected Compiler Generation, Proceedings of a Workshop, Aarhus, Denmark, January 1418, 1980; 01/1980 
Conference Proceeding: Parameterized Data Types in Algebraic Specification Languages (Short Version).
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ABSTRACT: Without AbstractAutomata, Languages and Programming, 7th Colloquium, Noordweijkerhout, The Netherland, July 1418, 1980, Proceedings; 01/1980 
Conference Proceeding: Programming Languages as Mathematical Objects.
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ABSTRACT: Without AbstractMathematical Foundations of Computer Science 1978, Proceedings, 7th Symposium, Zakopane, Poland, September 48, 1978; 01/1978  J. ACM. 01/1977; 24:6895.

Conference Proceeding: A Uniform Approach to Inductive Posets and Inductive Closure.
Mathematical Foundations of Computer Science 1977, 6th Symposium, Tatranska Lomnica, Czechoslovakia, September 59, 1977, Proceedings; 01/1977 
Conference Proceeding: Some Fundamentals of OrderAlgebraic Semantics.
Mathematical Foundations of Computer Science 1976, 5th Symposium, Gdansk, Poland, September 610, 1976, Proceedings; 01/1976 
Conference Proceeding: Factorizations, Congruences, and the Decomposition of Automata and Systems.
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ABSTRACT: Without AbstractMathematical Foundations of Computer Science, 3rd Symposium at Jadwisin near Warsaw, June 1722, 1974, Proceedings; 01/1974
Publication Stats
276  Citations  
428  Views  
1.07  Total Impact Points  
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Institutions

1983

IBM
 Thomas J. Watson Research Center
Armonk, NY, United States
