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Constructing Recursion Operators in Intuitionistic Type Theory
 Journal of Symbolic Computation
, 1984
"... MartinLöf's Intuitionistic Theory of Types is becoming popular for formal reasoning about computer programs. To handle recursion schemes other than primitive recursion, a theory of wellfounded relations is presented. Using primitive recursion over higher types, induction and recursion are for ..."
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Cited by 23 (5 self)
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MartinLöf's Intuitionistic Theory of Types is becoming popular for formal reasoning about computer programs. To handle recursion schemes other than primitive recursion, a theory of wellfounded relations is presented. Using primitive recursion over higher types, induction and recursion are formally derived for a large class of wellfounded relations. Included are < on natural numbers, and relations formed by inverse images, addition, multiplication, and exponentiation of other relations. The constructions are given in full detail to allow their use in theorem provers for Type Theory, such as Nuprl. The theory is compared with work in the field of ordinal recursion over higher types.
Decidability Extracted: SYNTHESIZING “CORRECTBYCONSTRUCTION” DECISION PROCEDURES FROM CONSTRUCTIVE PROOFS
, 1998
"... The topic of this thesis is the extraction of efficient and readable programs from formal constructive proofs of decidability. The proof methods employed to generate the efficient code are new and result in clean and readable Nuprl extracts for two nontrivial programs. They are based on the use of ..."
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Cited by 3 (0 self)
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The topic of this thesis is the extraction of efficient and readable programs from formal constructive proofs of decidability. The proof methods employed to generate the efficient code are new and result in clean and readable Nuprl extracts for two nontrivial programs. They are based on the use of Nuprl’s set type and techniques for extracting efficient programs from induction principles. The constructive formal theories required to express the decidability theorems are of independent interest. They formally circumscribe the mathematical knowledge needed to understand the derived algorithms. The formal theories express concepts that are taught at the senior college level. The decidability proofs themselves, depending on this material, are of interest and are presented in some detail. The proof of decidability of classical propositional logic is relative to a semantics based on Kleene’s strong threevalued logic. The constructive proof of intuitionistic decidability presented here is the first machine formalization of this proof. Theexposition reveals aspects of the Nuprl tactic collection relevant to the creation of readable proofs; clear extracts and efficient code are illustrated in the discussion of the proofs.
Extracting Recursion Operators in Nuprl's Type Theory
 Eleventh International Workshop on Logic based Program Synthesis, LOPSTR02, volume 2372 of LNCS
, 2001
"... In this paper we describe the extraction of efficient recursion schemes from proofs of wellfounded induction principles. This is part of a larger methodology ..."
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Cited by 2 (2 self)
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In this paper we describe the extraction of efficient recursion schemes from proofs of wellfounded induction principles. This is part of a larger methodology
A Foundation for Verified Software Development Systems
"... We describe a formalization of the metamathematics of programming in a higherorder calculus as a means to create verifiably correct implementations of program synthesis tools. Formal definitions and lemmata are used to raise the level of abstraction in formal reasoning to one comprehensible for pr ..."
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We describe a formalization of the metamathematics of programming in a higherorder calculus as a means to create verifiably correct implementations of program synthesis tools. Formal definitions and lemmata are used to raise the level of abstraction in formal reasoning to one comprehensible for programmers. Formal metatheorems make explicit the semantic knowledge contained in program derivation methods and serve as kernel of derived inference rules implementing these methods. By an example formalization of a strategy deriving global search algorithms we demonstrate the advantages of combining formal mathematics with an interactive theorem proving environment to develop powerful, flexible, and reliable systems for knowledgebased software development.