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Computational Foundations of Basic Recursive Function Theory
 Theoretical Computer Science
, 1988
"... The theory of computability, or basic recursive function theory as it is often called, is usually motivated and developed using Church's Thesis. Here we show that there is an alternative computability theory in which some of the basic results on unsolvability become more absolute, results on complet ..."
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Cited by 20 (7 self)
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The theory of computability, or basic recursive function theory as it is often called, is usually motivated and developed using Church's Thesis. Here we show that there is an alternative computability theory in which some of the basic results on unsolvability become more absolute, results on completeness become simpler, and many of the central concepts become more abstract. In this approach computations are viewed as mathematical objects, and the major theorems in recursion theory may be classified according to which axioms about computation are needed to prove them. The theory is a typed theory of functions over the natural numbers, and there are unsolvable problems in this setting independent of the existence of indexings. The unsolvability results are interpreted to show that the partial function concept, so important in computer science, serves to distinguish between classical and constructive type theories (in a different way than does the decidability concept as expressed in the ...
Collapsing Partial Combinatory Algebras
 HigherOrder Algebra, Logic, and Term Rewriting
, 1996
"... Partial combinatory algebras occur regularly in the literature as a framework for an abstract formulation of computation theory or recursion theory. In this paper we develop some general theory concerning homomorphic images (or collapses) of pca's, obtained by identification of elements in a pca. We ..."
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Cited by 12 (2 self)
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Partial combinatory algebras occur regularly in the literature as a framework for an abstract formulation of computation theory or recursion theory. In this paper we develop some general theory concerning homomorphic images (or collapses) of pca's, obtained by identification of elements in a pca. We establish several facts concerning final collapses (maximal identification of elements). `En passant' we find another example of a pca that cannot be extended to a total one. 1
Effective Applicative Structures
 In: Proceedings of the 6th biennial conference on Category Theory in Computer Science (CTCS'95). SpringerVerlag Lecture Notes in Computer Science 953 8195
, 1995
"... S. All local authors can be reached viaemail at theaddress lastname@cs.unibo.it. Written requests and comments should be addressed to tradmin@cs.unibo.it. UBLCS Technical Report Series 9320 An Information Flow Security Property for CCS, R. Focardi, R. Gorrieri, October 1993. 9321 A Classifica ..."
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Cited by 7 (2 self)
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S. All local authors can be reached viaemail at theaddress lastname@cs.unibo.it. Written requests and comments should be addressed to tradmin@cs.unibo.it. UBLCS Technical Report Series 9320 An Information Flow Security Property for CCS, R. Focardi, R. Gorrieri, October 1993. 9321 A Classification of Security Properties, R. Focardi, R. Gorrieri, October 1993. 9322 Real Time Systems: A Tutorial, F. Panzieri, R. Davoli, October 1993. 9323 A Scalable Architecture for Reliable Distributed Multimedia Applications, F. Panzieri, M. Roccetti, October 1993. 9324 WideArea Distribution Issues in Hypertext Systems, C. Maioli, S. Sola, F. Vitali, October 1993. 9325 On Relating Some Models for Concurrency, P. Degano, R. Gorrieri, S. Vigna, October 1993. 9326 Axiomatising ST Bisimulation Equivalence, N. Busi, R. van Glabbeek, R. Gorrieri, December 1993. 9327 A Theory of Processeswith Durational Actions, R. Gorrieri, M. Roccetti, E. Stancampiano, December1993. 941 Further Modifications t...
A Limiting First Order Realizability Interpretation
"... Constructive Mathematics might be regarded as a fragment of classical mathematics in which any proof of an existence theorem is equipped with a computable function giving the solution of the theorem. Limit Computable Mathematics (LCM) considered in this note is a fragment of classical mathematics ..."
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Cited by 5 (0 self)
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Constructive Mathematics might be regarded as a fragment of classical mathematics in which any proof of an existence theorem is equipped with a computable function giving the solution of the theorem. Limit Computable Mathematics (LCM) considered in this note is a fragment of classical mathematics in which any proof of an existence theorem is equipped with a function computing the solution of the theorem in the limit.
Completing Partial Combinatory Algebras with Unique HeadNormal Forms
, 1996
"... In this note, we prove that having unique headnormal forms is a sufficient condition on partial combinatory algebras to be completable. As application, we show that the pca of strongly normalizing CLterms as well as the pca of natural numbers with partial recursive function application can be exte ..."
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Cited by 3 (1 self)
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In this note, we prove that having unique headnormal forms is a sufficient condition on partial combinatory algebras to be completable. As application, we show that the pca of strongly normalizing CLterms as well as the pca of natural numbers with partial recursive function application can be extended to total combinatory algebras. 1.
Towards Limit Computable Mathematics
"... The notion of LimitComputable Mathematics (LCM) will be introduced. LCM is a fragment of classical mathematics in which the law of excluded middle is restricted to 1 0 2 formulas. We can give an accountable computational interpretation to the proofs of LCM. The computational content of LCMp ..."
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The notion of LimitComputable Mathematics (LCM) will be introduced. LCM is a fragment of classical mathematics in which the law of excluded middle is restricted to 1 0 2 formulas. We can give an accountable computational interpretation to the proofs of LCM. The computational content of LCMproofs is given by Gold's limiting recursive functions, which is the fundamental notion of learning theory. LCM is expected to be a right means for "Proof Animation," which was introduced by the first author [10]. LCM is related not only to learning theory and recursion theory, but also to many areas in mathematics and computer science such as computational algebra, computability theories in analysis, reverse mathematics, and many others.
Extending Partial Combinatory Algebras
, 1999
"... Introduction Consider a structure A = hA; s; k; \Deltai, where A is some set containing the distinguished elements s; k, equipped with a binary operation \Delta on A, called application, which may be partial. Notation 1.1. 1 Instead of a \Delta b we write ab; and in writing applicative expression ..."
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Cited by 1 (0 self)
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Introduction Consider a structure A = hA; s; k; \Deltai, where A is some set containing the distinguished elements s; k, equipped with a binary operation \Delta on A, called application, which may be partial. Notation 1.1. 1 Instead of a \Delta b we write ab; and in writing applicative expressions, the usual convention of association to the left is employed. So for elements a; b; c 2 A, the expression aba(ac) is short for ((a \Delta b) \Delta a) \Delta (a \Delta c). 2 ab # will mean that ab is defined; ab " means that ab is not defined. Obviously, an applicative expression
unknown title
"... They first noticed that Gold’s limiting recursive functions which was originally introduced to formulate the learning processes of machines, serve as approximation algorithms. Here, Gold’s limiting recursive function is of the form $f(x) $ such that $f(x)=y \Leftrightarrow\exists t_{0}\forall t>t_{0 ..."
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They first noticed that Gold’s limiting recursive functions which was originally introduced to formulate the learning processes of machines, serve as approximation algorithms. Here, Gold’s limiting recursive function is of the form $f(x) $ such that $f(x)=y \Leftrightarrow\exists t_{0}\forall t>t_{0}.g(t,x)=y\Leftrightarrow\lim_{t}g(t, x)=y$, $t $ where $g(t, x) $ is called a guessing function, and is a limit variable. Then, they proved that some limiting recursive functions approximate arealizer of a semiclassical principle $\neg\neg\exists y\forall x.g(x, y)=0arrow\exists y\forall x.g(x, y)=0$. Also, they showed impressive usages of the semiclassical principle for mathematics and for software synthesis. In this way, NakataHayashi opened up the possibility that limiting operations provide readability interpretation of semiclassical logical systems. They formulated the set of the limiting recursive functions as a Basic Recursive hnction Theory(brft, for short. Wagner[19] and Strong[16]). Then NakataHayashi carried out their readability interpretation using the BRFT.