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223
PVS: Combining Specification, Proof Checking, and Model Checking
, 1996
"... rem Proving and Typechecking The PVS specification language is based on classical, simply typed higherorder logic, but the type system has been augmented with subtypes and dependent types. Though typechecking is undecidable for the PVS type system, the PVS typechecker automatically checks for simp ..."
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Cited by 207 (4 self)
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rem Proving and Typechecking The PVS specification language is based on classical, simply typed higherorder logic, but the type system has been augmented with subtypes and dependent types. Though typechecking is undecidable for the PVS type system, the PVS typechecker automatically checks for simple type correctness and generates proof obligations corresponding to predicate subtypes. These proof obligations can be discharged through the use of the PVS proof checker. PVS also has parametric theories so that it is possible to capture, say, the notion of sorting with respect to arbitrary sizes, types, and ordering relations. By exploiting subtyping, dependent typing, and parametric theories, researchers at NASA Langley Research Center and SRI have developed a very general bitvector library. Paul Miner at NASA ? The development of PVS was funded by SRI International through IR&D funds. Various applications and customizations have been funded by NSF Grant CCR9300
Validity Checking for Combinations of Theories with Equality
, 1996
"... . An essential component in many verification methods is a fast decision procedure for validating logical expressions. This paper presents the algorithm used in the Stanford Validity Checker (SVC) which has been used to aid several realistic hardware verification efforts. The logic for this decision ..."
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Cited by 151 (23 self)
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. An essential component in many verification methods is a fast decision procedure for validating logical expressions. This paper presents the algorithm used in the Stanford Validity Checker (SVC) which has been used to aid several realistic hardware verification efforts. The logic for this decision procedure includes Boolean and uninterpreted functions and linear arithmetic. We have also successfully incorporated other interpreted functions, such as array operations and linear inequalities. The primary techniques which allow a complete and efficient implementation are expression sharing, heuristic rewriting, and congruence closure with interpreted functions. We discuss these techniques and present the results of initial experiments in which SVC is used as a decision procedure in PVS, resulting in dramatic speedups. 1 Introduction Decision procedures are emerging as a central component of formal verification systems. Such a procedure can be included as a component of a generalpurpos...
Alcoa: the alloy constraint analyzer
 In Proceedings of the 22nd. International Conference on Software Engineering
"... Alcoa is a tool for analyzing object models. It has a range of uses. At one end, it can act as a support tool for object model diagrams, checking for consistency of multiplicities and generating sample snapshots. At the other end, it embodies a lightweight formal method in which subtle properties of ..."
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Cited by 120 (7 self)
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Alcoa is a tool for analyzing object models. It has a range of uses. At one end, it can act as a support tool for object model diagrams, checking for consistency of multiplicities and generating sample snapshots. At the other end, it embodies a lightweight formal method in which subtle properties of behaviour can be investigated. Alcoa’s input language, Alloy, is a new notation based on Z. Its development was motivated by the need for a notation that is more closely tailored to object models (in the style of UML), and more amenable to automatic analysis. Like Z, Alloy supports the description of systems whose state involves complex relational structure. State and behavioural properties are described declaratively, by conjoining constraints. This makes it possible to develop and analyze a model incrementally, with Alcoa investigating the consequences of whatever constraints are given. Alcoa works by translating constraints to boolean formulas, and then applying stateoftheart SAT solvers. It can analyze billions of states in seconds.
Automating FirstOrder Relational Logic
, 2000
"... An analysis is described that can automatically find models of firstorder formulas with relational operators and scalar quantifiers. The formula is translated to a quantifierfree boolean formula that has a model exactly when the original formula has a model within a given scope (that is, involving ..."
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Cited by 116 (19 self)
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An analysis is described that can automatically find models of firstorder formulas with relational operators and scalar quantifiers. The formula is translated to a quantifierfree boolean formula that has a model exactly when the original formula has a model within a given scope (that is, involving no more than some finite number of atoms). The paper presents a simple logic and gives a compositional translation scheme. It reports on the use of Alcoa, a tool based on the scheme, to analyze a variety of specifications expressed in Alloy, an object modelling notation based on the logic.
Powerful Techniques for the Automatic Generation of Invariants
 In CAV
, 1996
"... . When proving invariance properties of programs one is faced with two problems. The first problem is related to the necessity of proving tautologies of the considered assertion language, whereas the second manifests in the need of finding sufficiently strong invariants. This paper focuses on the se ..."
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Cited by 89 (9 self)
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. When proving invariance properties of programs one is faced with two problems. The first problem is related to the necessity of proving tautologies of the considered assertion language, whereas the second manifests in the need of finding sufficiently strong invariants. This paper focuses on the second problem and describes techniques for the automatic generation of invariants. The first set of these techniques is applicable on sequential transition systems and allows to derive socalled local invariants, i.e. predicates which are invariant at some control location. The second is applicable on networks of transition systems and allows to combine local invariants of the sequential components to obtain local invariants of the global systems. Furthermore, a refined strengthening technique is presented that allows to avoid the problem of sizeincrease of the considered predicates which is the main drawback of the usual strengthening technique. The proposed techniques are illustrated by ex...
Model Checking Complete Requirements Specifications Using Abstraction
 Automated Software Engineering
, 1999
"... Although model checking has proven remarkably effective in detecting errors in hardware designs, its success in the analysis of software specifications has been limited. Model checking algorithms for hardware verification commonly use Binary Decision Diagrams (BDDs) to represent predicates involving ..."
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Cited by 70 (19 self)
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Although model checking has proven remarkably effective in detecting errors in hardware designs, its success in the analysis of software specifications has been limited. Model checking algorithms for hardware verification commonly use Binary Decision Diagrams (BDDs) to represent predicates involving the many Boolean variables commonly found in hardware descriptions. Unfortunately, BDD representations may be less effective for analyzing software specifications, which usually contain not only Booleans but variables spanning a wide range of data types. Further, software specifications typically have huge, sometimes infinite, state spaces that cannot be model checked directly using conventional symbolic methods. One promising but largely unexplored approach to model checking software...
Automatic Generation of Program Specifications
 In ISSTA 2002, Proceedings of the 2002 International Symposium on Software Testing and Analysis
, 2002
"... Producing specifications by dynamic (runtime) analysis of program executions is potentially unsound, because the analyzed executions may not fully characterize all possible executions of the program. In practice, how accurate are the results of a dynamic analysis? This paper describes the results of ..."
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Cited by 64 (15 self)
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Producing specifications by dynamic (runtime) analysis of program executions is potentially unsound, because the analyzed executions may not fully characterize all possible executions of the program. In practice, how accurate are the results of a dynamic analysis? This paper describes the results of an investigation into this question, determining how much specifications generalized from program runs must be changed in order to be verified by a static checker.
Java Program Verification via a Hoare Logic with Abrupt Termination
 Fundamental Approaches to Software Engineering (FASE 2000), number 1783 in LNCS
, 2000
"... This paper formalises a semantics for statements and expressions (in sequential imperative languages) which includes nontermination, normal termination and abrupt termination (e.g. because of an exception, break, return or continue). This extends the traditional semantics underlying e.g. Hoare logi ..."
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Cited by 62 (6 self)
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This paper formalises a semantics for statements and expressions (in sequential imperative languages) which includes nontermination, normal termination and abrupt termination (e.g. because of an exception, break, return or continue). This extends the traditional semantics underlying e.g. Hoare logic, which only distinguishes termination and nontermination. An extension of Hoare logic is elaborated that includes means for reasoning about abrupt termination (and sideeffects). It prominently involves rules for reasoning about while loops, which may contain exceptions, breaks, continues and returns. This extension applies in particular to Java. As an example, a standard pattern search algorithm in Java (involving a while loop with returns) is proven correct using the prooftool PVS.
Experiences Using Lightweight Formal Methods for Requirements Modeling
 IEEE Transactions on Software Engineering
, 1998
"... Additional information is available from the NASA Software IV&V Facility on the ..."
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Cited by 53 (7 self)
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Additional information is available from the NASA Software IV&V Facility on the
On Shostak's Decision Procedure for Combinations of Theories
, 1996
"... Decision procedures are increasingly being employed for deciding or simplifying propositional combinations of ground equalities involving uninterpreted function symbols, linear arithmetic, arrays, and other theories. Two approaches for constructing decision procedures for combinations of ground theo ..."
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Cited by 52 (8 self)
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Decision procedures are increasingly being employed for deciding or simplifying propositional combinations of ground equalities involving uninterpreted function symbols, linear arithmetic, arrays, and other theories. Two approaches for constructing decision procedures for combinations of ground theories were pioneered in the late seventies. In the approach of Nelson and Oppen, decision procedures for two disjoint theories are combined by introducing variables to name subterms and iteratively propagating any deduced equalities between variables from one theory to another. Shostak employs a different approach that works far more efficiently in practice. He uses an optimized implementation of the congruence closure procedure for ground equality over uninterpreted function symbols to combine theories that are canonizable and algebraically solvable. Many useful theories have these properties. Shostak's algorithm is subtle and complex and his description of this procedure is lacking in ri...