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36
Observational logic
 IN ALGEBRAIC METHODOLOGY AND SOFTWARE TECHNOLOGY (AMAST'98
, 1999
"... We present an institution of observational logic suited for statebased systems specifications. The institution is based on the notion of an observational signature (which incorporates the declaration of a distinguished set of observers) and on observational algebras whose operations are required ..."
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Cited by 56 (10 self)
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We present an institution of observational logic suited for statebased systems specifications. The institution is based on the notion of an observational signature (which incorporates the declaration of a distinguished set of observers) and on observational algebras whose operations are required to be compatible with the indistinguishability relation determined by the given observers. In particular, we introduce a homomorphism concept for observational algebras which adequately expresses observational relationships between algebras. Then we consider a flexible notion of observational signature morphism which guarantees the satisfaction condition of institutions w.r.t. observational satisfaction of arbitrary firstorder sentences. From the proof theoretical point of view we construct a sound and complete proof system for the observational consequence relation. Then we consider structured observational specifications and we provide a sound and complete proof system for such specifications by using a general, institutionindependent result of [6].
Circular Coinductive Rewriting
 In Proceedings of Automated Software Engineering 2000
, 2000
"... Circular coinductive rewriting is a new method for proving behavioral properties, that combines behavioral rewriting with circular coinduction. This method is implemented in our new BOBJ behavioral specification and computation system, which is used in examples throughout this paper. These examples ..."
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Cited by 51 (13 self)
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Circular coinductive rewriting is a new method for proving behavioral properties, that combines behavioral rewriting with circular coinduction. This method is implemented in our new BOBJ behavioral specification and computation system, which is used in examples throughout this paper. These examples demonstrate the surprising power of circular coinductive rewriting. The paper also sketches the underlying hidden algebraic theory and briefly describes BOBJ and some of its algorithms.
Observer Complete Definitions are Behaviourally Coherent
 OBJ/CAFEOBJ/MAUDE AT FORMAL METHODS '99
, 1999
"... We consider observational specifications of statebased systems which incorporate the declaration of a distinguished set of observer operations. These observers determine an indistinguishability relation for states which is called "observational equality". An important requirement for ..."
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Cited by 33 (6 self)
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We consider observational specifications of statebased systems which incorporate the declaration of a distinguished set of observer operations. These observers determine an indistinguishability relation for states which is called "observational equality". An important requirement for the nonobserver operations is the compatibility with the observational equality. In the CafeOBJ language (and in extended hidden algebra) this property is called "behavioural coherence". In this presentation we introduce the notion of an "observer complete definition" and we show that any (nonobserver) operation which is defined using this pattern is behaviourally coherent. We also discuss some consequences of this result for relating observational logic and extended hidden algebra semantics and for proving the correctness of observational implementations.
Hidden Congruent Deduction
 Automated Deduction in Classical and NonClassical Logics
, 1998
"... This paper presents some techniques of this kind in the area called hidden algebra, clustered around the central notion of coinduction. We believe hidden algebra is the natural next step in the evolution of algebraic semantics and its first order proof technology. Hidden algebra originated in [7], a ..."
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Cited by 25 (20 self)
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This paper presents some techniques of this kind in the area called hidden algebra, clustered around the central notion of coinduction. We believe hidden algebra is the natural next step in the evolution of algebraic semantics and its first order proof technology. Hidden algebra originated in [7], and was developed further in [8, 10, 3, 12, 5] among other places; the most comprehensive survey currently available is [12]
Incompleteness of Behavioral Logics
, 2000
"... Incompleteness results for behavioral logics are investigated. We show that there is a basic finite behavioral specification for which the behavioral satisfaction problem is not recursively enumerable, which means that there are no automatic methods for proving all true statements; in particular, be ..."
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Cited by 23 (8 self)
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Incompleteness results for behavioral logics are investigated. We show that there is a basic finite behavioral specification for which the behavioral satisfaction problem is not recursively enumerable, which means that there are no automatic methods for proving all true statements; in particular, behavioral logics do not admit complete deduction systems. This holds for all of the behavioral logics of which we are aware. We also prove that the behavioral satisfaction problem is not corecursively enumerable, which means that there is no automatic way to refute false statements in behavioral logics. In fact we show stronger results, that all behavioral logics are # 0 2 hard, and that, for some data algebras, the complexity of behavioral satisfaction is not even arithmetic; matching upper bounds are established for some behavioral logics. In addition, we show for the fixeddata case that if operations mayhave more than one hidden argument, then final models need not exist, so that the coalgebraic flavor of behavioral logic is lost.
Conditional Circular Coinductive Rewriting with Case Analysis
, 2002
"... We argue for an algorithmic approach to behavioral proofs, review the hidden algebra approach, develop circular coinductive rewriting for conditional goals, extend it with case analysis, and give some examples. ..."
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Cited by 19 (1 self)
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We argue for an algorithmic approach to behavioral proofs, review the hidden algebra approach, develop circular coinductive rewriting for conditional goals, extend it with case analysis, and give some examples.
Social and Semiotic Analyses for Theorem Prover User Interface Design
 Formal Aspects of Computing
, 1999
"... We describe an approach to user interface design based on ideas from social science, narratology (the theory of stories), cognitive science, and a new area called algebraic semiotics. Social analysis helps to identify certain roles for users with their associated requirements, and suggests ways to m ..."
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Cited by 18 (11 self)
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We describe an approach to user interface design based on ideas from social science, narratology (the theory of stories), cognitive science, and a new area called algebraic semiotics. Social analysis helps to identify certain roles for users with their associated requirements, and suggests ways to make proofs more understandable, while algebraic semiotics, which combines semiotics with algebraic specification, provides rigorous theories for interface functionality and for a certain technical notion of quality. We apply these techniques to designing user interfaces for a distributed cooperative theorem proving system, whose main component is a website generation and proof assistance tool called Kumo. This interface integrates formal proving, proof browsing, animation, informal explanation, and online background tutorials, drawing on a richer than usual notion of proof. Experience with using the interface is reported, and some conclusions are drawn.
Proof Scores in the OTS/CafeOBJ method
 In Proc. of The 6th IFIP WG6.1 International Conference on Formal Methods for Open ObjectBased Distributed Systems (FMOODS 2003), volume 2884 of LNCS
, 2003
"... Abstract. A way to write proof scores showing that distributed systems have invariant properties in algebraic specification languages is described, which has been devised through several case studies. The way makes it possible to divide a formula stating an invariant property under discussion into r ..."
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Cited by 16 (13 self)
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Abstract. A way to write proof scores showing that distributed systems have invariant properties in algebraic specification languages is described, which has been devised through several case studies. The way makes it possible to divide a formula stating an invariant property under discussion into reasonably small ones, each of which is proved by writing proof scores individually. This relieves the load to reduce logical formulas and can decrease the number of subcases into which the case is split in case analysis.
CIRC : A Circular Coinductive Prover
 In CALCO, LNCS 4624
, 2007
"... Abstract. CIRC is an automated circular coinductive prover implemented as an extension of Maude. The circular coinductive technique that forms the core of CIRC is discussed, together with a highlevel implementation using metalevel capabilities of rewriting logic. To reflect the strength of CIRC i ..."
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Cited by 16 (0 self)
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Abstract. CIRC is an automated circular coinductive prover implemented as an extension of Maude. The circular coinductive technique that forms the core of CIRC is discussed, together with a highlevel implementation using metalevel capabilities of rewriting logic. To reflect the strength of CIRC in automatically proving behavioral properties, an example defining and proving properties about infinite streams of infinite binary trees is shown. CIRC also provides limited support for automated inductive proving, which can be used in combination with coinduction. 1
Hidden Algebra for Software Engineering
 PROCEEDINGS COMBINATORICS, COMPUTATION AND LOGIC
, 1999
"... This paper is an introduction to recent research on hidden algebra and its application to software engineering; it is intended to be informal and friendly, but still precise. We first review classical algebraic specification for traditional "Platonic" abstract data types like integers, ve ..."
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Cited by 14 (0 self)
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This paper is an introduction to recent research on hidden algebra and its application to software engineering; it is intended to be informal and friendly, but still precise. We first review classical algebraic specification for traditional "Platonic" abstract data types like integers, vectors, matrices, and lists. Software engineering also needs changeable "abstract machines," recently called "objects," that can communicate concurrently with other objects through visible "attributes" and statechanging "methods." Hidden algebra is a new development in algebraic semantics designed to handle such systems. Equational theories are used in both cases, but the notion of satisfaction for hidden algebra is behavioral, in the sense that equations need only appear to be true under all possible experiments; this extra flexibility is needed to accommodate the clever implementations that software engineers often use to conserve space and/or time. The most important results in hidden algebra are ...