R. D. Nicola and M. C. B. Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34(1--2):83--133, Nov. 1984.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....however in this paper we validate them by relating the fair and quiescent preorders to the theory of testing. 2. 3 The Theory of Testing A different method for comparing transition systems is based on the observation of the interactions between a transition system and an external experimenter [3, 5, 7]. An experimenter for a transition system T is a transition system E, compatible with T , whose external actions are those of T plus an action w, called the success action. An experiment x is an execution of TkE which is infinite or ends in a deadlocked state (complete execution) An experiment x ....

R. De Nicola and M. Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34:83--133, 1984.

....can be performed on a Linda program, and we also define when a program passes or fails the test. Two programs will be equivalent iff they pass the 24 same set of tests. This equivalence has been proposed for process description languages by De Nicola and Hennessy with the name testing equivalence [26]. A nice introduction to testing equivalence can be found in [17] Since the Linda calculus defined so far has been proposed with the aim of describing interactions with the tuple space and Linda programs are supposed to interact mainly with Linda programs, it is reasonable to state that Linda ....

Rocco De Nicola and M Hennessy. Testing equivalence for processes. Theoretical Computer Science, 34:83--133, 1983.

....equivalence. For example, a process that simply performs an action a and then stops ought to be the same as one that has several different ways of doing a s and then stopping, since one a or stopped process is the same as another. A wide variety of notions of equivalence have been proposed, e.g.[28,31,20,5,21,27,41], appropriate for different kinds of process algebras and conceptual settings. Process equivalences can be partially ordered by fineness: finer notions make more distinctions between processes; coarser ones consider more processes identical. Both fine and coarse notions are useful in theory and ....

R. de Nicola and M. C. B. Hennessy. Testing equivalences for processes. Theoretical Computer Sci., 34(2/3):83--133, 1984.

....FTS result came first. In any case, this is rather a strong result at first sight, because observational equivalence is a very strong equivalence. In fact, we found that observational equivalence is particularly suited to describing the relation between the two. For example, testing equivalences [dNH84] are not suitable because they distinguish FTS from the perfect system because of the possibility of repeated failure, the former is capable of infinite chatter while the latter is not. Observational equivalence ignores this difference, but is otherwise much stronger than testing equivalences. ....

Rocco de Nicola and Matthew Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34:83, 1984.

....This cannot be matched by p since it has to receive, and become 5 0 6 q. Despite these differences, the definition of is motivated as in CCS, because s are autonomous and silent. That is in fact an observational equivalence would be established by characterising it as a testing equivalence [dNH84, Abr87]. This has not yet been done, but the present definition was arrived at via testing examples [Pra93a] and is consistent with them. Proposition20 Weak bisimulation laws. 1. 0 0 2. w p w p 3. x p x p x p 4. f (f s) f s 16 It is a conjecture that the above laws ....

Rocco de Nicola and Matthew Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34:83, 1984.

....properties such as secrecy and authenticity can be accounted for in equational terms, for instance by reflecting insensitivity of environments to changes in trusted values. However, due to the explicit treatment of encryption and decryption a rather non standard version of testing equivalence [12] has to be appealed to for the correctness proofs. This is avoided in our approach, due to our use of second order communication to account for encryption and decryption. In [2] several alternative representations of encryption and decryption in the calculus are discussed, including one, using ....

R. De Nicola and M. Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34:83--133, 1984.

....at first sight, because observational equivalence is a very strong equivalence. In fact, we found that observational equivalence is particularly suited to describing Combinators and Bisimulation Proofs for Restartable Systems 17 the relation between the two. For example, testing equivalences [dNH84] are not suitable because they distinguish FTS from the perfect system because of the possibility of repeated failure, the former is capable of infinite chatter while the latter is not. Observational equivalence ignores this difference, but is otherwise much stronger than testing equivalences. ....

Rocco de Nicola and Matthew Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34:83, 1984.

....is faster than h0; a:0i 5 . However, our timed bisimilarity cannot represents such faster than relation over processes on the basis of their relative speeds. In this section we investigate preorder relations which represents such faster than relation based on the notion of testing equivalence [4]. 5.1 Timed Testing System Here we define the semantics for RtCCS with the notion of testing equivalence. 10 Definition 5 (Tester) We assume that a tester (experimenter) is modeled by an labelled transition system hT ; ACT [ fwg; 70 i. The set of the testers is denoted by T and ranged over by ....

....The set of computations starting from t 0 jjp 0 is denoted as Comp(t; p) 11 5.2 Timed Testing Preorders In this subsection, we investigate timed testing preorders. The definitions of the timed testing preorders are defined in the essentially same manner as the testing preorder relation in [4]. For simplicity, we restrict our attention to divergence free processes. Definition 9 Result(t; p) is the result of applying a tester t to a process p. It is a subset of f ; g where denotes a successful computation and a unsuccessful computation. 2 Result(t; p) if there exists c 2 ....

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de Nicola,R. and Hennessy,M., Testing equivalence for processes, Theoretical Computer Science, Vol.34, 1984. 13

....the other transformations) only w.r.t. barbed equivalence and congruence. But we believe that C respects most of 155 Chapter 7. Conclusions and Future Work 156 the well known weak equivalences which admit a uniform definition over higherorder and first order calculi, such as testing equivalence [DH84], or refusal semantics [Phi87] The reason for this is the close operational correspondence between encoded and encoding agents shown in Lemma 5.2.2. Indeed C might even be used to define equivalences in HO. Take for instance trace semantics as defined in [Hoa85] or causal bisimulation [DD89] ....

R. De Nicola and R. Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34:83--133, 1984.

....2 valued transition relations. These preorders are based on the branching structure of processes (ready simulation [7] bisimulation [21] on execution sequences (partial traces, completed traces, accepting traces) or on decorated versions of execution sequences (ready pairs [22] failure pairs [9, 11], ready traces [2, 25] failure traces [23] In [15] van Glabbeek classi ed most equivalences and preorders for concrete, sequential processes 1 that occur in the literature, and motivated them by means of testing scenarios, phrased in terms of button pushing experiments on generative and ....

R. De Nicola & M. Hennessy (1984): Testing equivalences for processes. Theoretical Computer Science 34, pp. 83-133.

....2 R, then q 1 p 1 if and only if q 2 p 2 A 1 and A 2 are strongly bisimilar, denoted A 1 = bis A 2 , if there exists a strong bisimulation between A 1 and A 2 . 2 2. 3 A Standard Testing Framework We will now introduce a framework for testing which is mostly inspired by De Nicola and Hennessy [2]. It is mostly standard for labelled transition systems, though we adapt it to infinite automata in the same way we did in the last section for equivalences and preorders. As the infinite automata contain explicit termination information, it is possible to simplify the approach presented in [2] ....

....[2] It is mostly standard for labelled transition systems, though we adapt it to infinite automata in the same way we did in the last section for equivalences and preorders. As the infinite automata contain explicit termination information, it is possible to simplify the approach presented in [2]. What we are going to formalise is a testing preorder, one of the better known implementation relations used in formal systems design. The general idea is that users of a given system should be flexible enough to deal with all the specified possible responses of the system. The interaction ....

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R. De Nicola and M.C.B. Hennessy. Testing Equivalences for Processes. Theoretical Computer Science, 34:83--133, 1984.

....A.3 Proofs of Section 6 . 53 A.4 Proofs of Section 7 . 57 2 1 Introduction There is a long tradition in de ning process re nement theories (see, e.g. [7, 10, 20]) essentially based on the idea that, given two processes S and I, I is an implementation of S if I is more deterministic (or equivalent) according to the chosen semantics. Still, both S and I belong conceptually to the same abstraction level, as the actions they perform belong to the same ....

R. De Nicola and M. C. B. Hennessy. Testing equivalences for processes. Theoretical Comput. Sci., 34:83-133, 1984.

....2] The underlying idea is that two processes are equivalent if and only if they cannot be distinguished by any process that does not know the secret values. It is basically a weaker version of classical testing equivalence where equivalent processes should be indistinguishable by any environment [5]. We de ne the notion of experiment as given in the spi calculus. A test is a couple (T ; where T is a process called tester and is a barb, i.e. a channel c or c . We say that a process P immediately passes a test (T ; denoted by P k T # ) i for some message m we have P k T m . ....

R. De Nicola and M. Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34:83-133, 1984.

....semantics is introduced in Brookes, Hoare Roscoe [13] and used in the construction of a model for the system description language CSP Introduction 5 (Hoare [29, 31] It is finer than completed trace semantics. The semantics based on testing equivalences, as developed in De Nicola Hennessy [17], coincides with failures semantics on the domain of finitely branching, concrete, sequential processes, as do the semantics of Kennaway [34] and Darondeau [15] This has been established in De Nicola [16] In Olderog Hoare [40] readiness semantics is presented, which is slightly finer than ....

....2 F ) 8a 2 X : n a; n = 62 F. That F5 holds follows from the observation that I(root(g) fa 2 Act j = n a; n = 2 F (g)g for g 2 j G. Alternative characterizations In De Nicola [16] several equivalences, that were proposed in Kennaway [34] Darondeau [15] and De Nicola Hennessy [17], are shown to coincide with failures semantics on the domain of finitely branching transition systems without internal moves. For this purpose he uses the following alternative characterization of failures equivalence. Definition 4.4 Write p after oe MUST X if for each q 2 IP with p oe Gamma ....

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R. De Nicola & M. Hennessy (1984): Testing equivalences for processes. Theoretical Computer Science 34, pp. 83--133.

....relations realized through the practical testing of systems come from a family of parameterized implementation relations. We will also show that for glass box testing, implementation relations parameterized by test purposes converge to the may testing preorder of DeNicola and Hennessy [7], while for black box testing, implementation relations parameterized by test cases converge to a maytesting preorder of the behavior visible at the interface to the environment. 1 Motivation When developing concurrent systems with formal methods, the notion of correctness of an implementation ....

....with formal methods, the notion of correctness of an implementation with respect to a specication plays a major role. Many of such implementation relations can be found in literature, e.g. bisimulation equivalence [6] failure equivalence and preorder [4] testing equivalence and preorder [7], as well as many others [11] To ensure properties of implementations, given implementation relations between a speci cation and its implementation have to be checked. For implementations for which a formal model exists this can be done by tools like the Concurrency Workbench [2] Yet, most ....

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R. De Nicola and M. Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34:83133, 1984.

....1. Introduction. 2. Basic definitions. 3. Proof rules for vertical implementation. 4. Vertical bisimulation. 5. Abstraction. 6. Open terms. 7. Examples. 8. Evaluation and future extensions. 1. INTRODUCTION There is a long tradition in defining process refinement theories (see, e.g. [8, 11, 29]) essentially based on the idea that, given two processes S and I , I is an implementation of S if I is more deterministic (or equivalent) according to the chosen semantics. Still, both S and I belong conceptually to the same abstraction level, as the actions they perform belong to the same ....

R. De Nicola and M. C. B. Hennessy. Testing equivalences for processes. Theoretical Comput. Sci., 34:83--133, 1984.

....[Mil80] is a branching time, interleaving based, intensional equivalence, while observational equivalence [Mil80] is a branching time, interleaving based extensional equivalence. Other noteworthy relations include the failures testing relations (linear time, interleaving, extensional) BHR84, DNH84] and pomset equivalence (linear time, truly concurrent, extensional) Pra86] Interested readers are referred to [Gla90] for a detailed study of the relationship among different equivalences. 5 These relations may also be used to bridge the gap between intensional and extensional models of ....

R. De Nicola and M. Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34:83--133, 1984.

....public channels. The static test amounts to checking that the data that may be sent along public channels can only be made of public components. 14 Another notion of secrecy has been previously used by Abadi, in [1] to obtain a non interference property, formalized in terms of testing equivalence [13, 9]. Roughly, a process P (x) i.e. a process where the variable x is free) does not interfere on x if a second process Q cannot distinguish running in parallel with P (M) from running in parallel with P (M # ) for every message M and M # . There, type soundness guarantees that there is no ....

R. De Nicola and M.C.B. Hennessy. Testing equivalence for processes. Theoretical Computer Science, 34:83--133, 1984.

....and secrecy rigorous. For instance, according to [2] a way of asserting that a protocol, represented by a process term P (d) keeps datum d secret is requiring that P (d) be equivalent to P (d 0 ) for every other d 0 . Observational equivalences based on context closure, like may testing [6, 3, 2] and barbed equivalence [11] appear to be appropriate in this setting. The intuition behind them is precisely that no external context (which 1 2 in the present setting can be read as attacker ) may notice any difference when running in parallel with P (d 0 ) or P (d) The definitions of ....

R. De Nicola, M.C.B. Hennessy. Testing Equivalence for Processes. Theoretical Computers Science, 34:83-133, Elsevier, 1984.

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R. D. Nicola and M. C. B. Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34(1--2):83--133, Nov. 1984.

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R. D. Nicola and M. C. B. Hennessy. Testing equivalences for processes. Theoretical Computer Science, 34(1--2):83--133, Nov. 1984.

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R. D. Nicola, M. C. B. Hennessy, Testing equivalences for processes, Theoretical Computer Science 34 (1-2) (1984) 83--133. 33

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R. D. Nicola and M. C. B. Hennessy. Testing equivalence for processes. Theoretical Computer Science, 34:83--133, 1984.

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R. D. Nicola and M. C. B. Hennessy. Testing equivalence for processes. Theor. Comput. Sci., 34:83--133, 1984.

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R. D. Nicola and M. C. B. Hennessy. Testing equivalence for processes. Theoretical Computer Science, 34:83 -- 133, 1984.

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