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Five axioms of alphaconversion
 Ninth international Conference on Theorem Proving in Higher Order Logics TPHOL
, 1996
"... Abstract. We present five axioms of namecarrying lambdaterms identified up to alphaconversion—that is, up to renaming of bound variables. We assume constructors for constants, variables, application and lambdaabstraction. Other constants represent a function Fv that returns the set of free variab ..."
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Cited by 51 (0 self)
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Abstract. We present five axioms of namecarrying lambdaterms identified up to alphaconversion—that is, up to renaming of bound variables. We assume constructors for constants, variables, application and lambdaabstraction. Other constants represent a function Fv that returns the set of free variables in a term and a function that substitutes a term for a variable free in another term. Our axioms are (1) equations relating Fv and each constructor, (2) equations relating substitution and each constructor, (3) alphaconversion itself, (4) unique existence of functions on lambdaterms defined by structural iteration, and (5) construction of lambdaabstractions given certain functions from variables to terms. By building a model from de Bruijn’s nameless lambdaterms, we show that our five axioms are a conservative extension of HOL. Theorems provable from the axioms include distinctness, injectivity and an exhaustion principle for the constructors, principles of structural induction and primitive recursion on lambdaterms, Hindley and Seldin’s substitution lemmas and
Automated Theorem Proving in Support of Computer Algebra: Symbolic Definite Integration as a Case Study
"... We assess the current state of research in the application of computer aided formal reasoning to computer algebra, and argue that embedded verification support allows users to enjoy its benefits without wrestling with technicalities. We illustrate this claim by considering symbolic definite integrat ..."
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Cited by 10 (5 self)
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We assess the current state of research in the application of computer aided formal reasoning to computer algebra, and argue that embedded verification support allows users to enjoy its benefits without wrestling with technicalities. We illustrate this claim by considering symbolic definite integration, and present a verifiable symbolic definite integral table look up: a system which matches a query comprising a definite integral with parameters and side conditions, against an entry in a verifiable table and uses a call to a library of lemmas about the reals in the theorem prover PVS to aid in the transformation of the table entry into an answer. We present the full model of such a system as well as a description of our prototype implementation showing the efficacy of such a system: for example, the prototype is able to obtain correct answers in cases where computer algebra systems [CAS] do not. We extend upon Fateman's webbased table by including parametric limits of integration and queries w...
VSDITLU: a verifiable symbolic definite integral table lookup
, 1999
"... We present a verifiable symbolic de nite integral table lookup: a system which matches a query, comprising a definite integral with parameters and side conditions, against an entry in a verifiable table and uses a call to a library of facts about the reals in the theorem prover PVS to aid in the tra ..."
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Cited by 2 (1 self)
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We present a verifiable symbolic de nite integral table lookup: a system which matches a query, comprising a definite integral with parameters and side conditions, against an entry in a verifiable table and uses a call to a library of facts about the reals in the theorem prover PVS to aid in the transformation of the table entry into an answer. Our system is able to obtain correct answers in cases where standard techniques implemented in computer algebra systems fail. We present the full model of such a system as well as a description of our prototype implementation showing the efficacy of such a system: for example, the prototype is able to obtain correct answers in cases where computer algebra systems [CAS] do not. We extend upon Fateman's webbased table by including parametric limits of integration and queries with side conditions.
Formally Verified Building Blocks in Functional Logic Diagrams for Emergency Shutdown System Design
, 1995
"... The task of safeguarding systems is to bring processes from dangerous into safe states. A special class of safeguarding systems are emergency shutdown systems (ESD), which, until now, are only implemented in inherently fail safe hardwired forms. Despite their high reliability, there is an urgent ind ..."
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The task of safeguarding systems is to bring processes from dangerous into safe states. A special class of safeguarding systems are emergency shutdown systems (ESD), which, until now, are only implemented in inherently fail safe hardwired forms. Despite their high reliability, there is an urgent industrial need to replace them by more flexible systems. Therefore, in an earlier work, a dedicated programmable logic controller (PLC) was designed, which directly supports functional logic diagrams (FLD), the traditional and user oriented graphical programming paradigm of ESDs, in its architecture. In this paper we give a formal correctness proof of the functional building blocks occurring in FLDs specifying ESDs. For this task Isabelle/HOL is used as a mechanical proof assistant. In a final step, safety licensing of ESD software can easily be carried through by back translation. 1 Introduction Many technical systems have the potential of disastrous effects on the environment, equipment, or...