M. Hennessy and T. Regan. A Temporal Process Algebra. In FORTE '90, Third International Conference on Formal Description Techniques, Madrid, November 5-8, pp. 25-40, 1990. 16  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of a combination of CCS (for prefixing and recursion) and ACP (for ffi, choice, parallel and encapsulation) with a unique feature, the unit delay operator. In the following presentation, the classification criterion is the standard algebra extended. 7. 1 Extensions of CCS Hennesy and Regan [HR90] present a process algebra TPL, which is an extension of CCS with a time action oe, playing the role of in ATP. An important difference with our model is that non internal actions a other than oe may be delayed (a:t a:t) The maximal progress assumption is adopted in TPL, that is, pjq may ....

....the same sequence from p is N iljb:N il, and the processes N iljoe:b:N il and N iljb:N il are not equivalent. Thus, it is not possible to have a law such as the expansion theorem. Yi [Wan90] describes another extension of CCS, called TCCS (Timed CCS) which is very close to the proposal of [HR90], in the sense that the process ff:P can let time pass before executing ff, whereas :P cannot. The important difference is that this work deals with continuous time; therefore a set of time events ffl(t) where t is a positive real number) is considered, rather than a time action. The process ....

[Article contains additional citation context not shown here]

M. Hennessy and T. Regan. A Temporal Process Algebra. Technical Report 2/90, University of Sussex, April 1990.

....of such systems are frequently altered depending on implementations. In such cases, we must guarantee that the system s essential behaviour would not be changed. In the latest years many languages have been proposed to describe real time prop erties [5 10] For example, timed extensions of CCS[5 7], introduced several primi tive operators such as delay and timeout operators to describe real time properties. However, in these languages, even describing a simple time constraint that some action has to be done within a given time interval yields to a complicated descrip tion. Although ....

M. Hennessy and T. Regan, "A temporal process algebra," in Formal Description Techniques, III, pp. 33-48, IFIP, North-Holland, 1991.

.... P 0 (t) P t Gamma P Q a Gamma Q 0 P Q a Gamma Q 0 P s Gamma P 0 (t) P s t Gamma P 0 P t Gamma P 0 ; Q t Gamma Q 0 P Q t Gamma P 0 Q 0 As further examples of classes of timed transition systems can serve TCSP [9, 10, 11] TiCCS [12] TPL [13, 14], U LOTOS [15] ATP [4] Definition 2.4 Let T be a timed transition system. For any L L, s; s 0 2 S, w = a 1 : an 2 A we say that 1: s L Gamma s 0 iff 9l 2 L:s l Gamma s 0 2: s (a;d) Gamma s 0 iff 9s 1 ; s 2 2 S; d 1 ; d 2 2 D: s d1 Gamma s 1 s 1 a Gamma s ....

Hennessy, M. and Regan, T.: A Temporal Process Algebra. Technical Report 2/90, University if Sussex, UK, 1990.

....the notion of time are being used widely in specifying and verifying concurrent systems. To expand their usefulness to real time systems, several real time process algebras have been developed by adding the notion of time and including a set of timing operators; e.g. Davies and Schneider (1989) Hennessy and Regan (1990), Moller and Tofts (1990) Yi (1991) and Nicollin and Sifakis (1994) The most salient aspect of process algebras is that they support the modular specification and verification of a system. This is due to the algebraic laws that form a compositional proof system, and thus, it is possible to ....

....allow execution of its second operand only in the case where the environment is not ready to allow the first component to proceed. A set of equational laws for bisimulation is given and its soundness and completeness are proved. A bi level priority semantics for CCS is treated in (Cleaveland and Hennessy, 1990), in which events are divided into two subsets: those of low priority (e.g. a; b) and those of high priority (e.g. a; b) Events may synchronize only with inverses of the same priority, which limits the range of priorities to a two element, total order. When synchronization occurs between ....

Hennessy, M., and Regan, T. (1990), "A Temporal Process Algebra," Technical Report 2/90, Univ. of Sussex.

.... only a few of a long list of references) Another well studied non interleaving qualitative aspect concerns the description of the localities where processes are placed (among the other proposals, see [8,1,2,29] Quantitative descriptions include transition systems that express temporal aspects [22,30,19,21,16], probabilistic aspects [34,25] and stochastic ones [20,23,3,9,31] Besides its interest in se, an SOS semantics for causality is relevant because it is paradigmatic for others qualitative, non interleaving description of concurrent systems, as well as for some of the quantitative ones. In ....

M. Hennessy and T. Regan. A temporal process algebra. Technical Report 2/90, University of Sussex, 1990.

....TCSP [24, 25] is an extension of the language CSP [34] In real time programming the correctness of a program depends not only on the flow of control. The program should also meet its timing constraints [46] Therefore new semantic models should be developed. Several models both operational [4, 28, 32] and denotational [27, 37, 43] have already been provided. In this paper a simple real time programming language is studied. Apart from the traditional programming constructs, this language incorporates timed atomic actions and integration. 1 full version of [22] 2 electronic mail address: ....

M. Hennessy and T. Regan. A Temporal Process Algebra. Report 2-90, University of Sussex, Brighton (1990).

....on a process calculus and analyzes the essential features of object based concurrency. Many theoretical models for real time computing have been explored in temporal logic, timed Petri nets, and denotational semantics frameworks based on linear history semantics. More recently, several studies [7, 6, 10, 15, 13, 20] developed the temporal models based on process calculi such as CCS and ACP. Milner s SCCS [10] is a calculus for synchronous processes based on the idea that each atomic action takes one unit of time. The concurrent agents of SCCS must essentially pro2 ceed in lockstep and at every instant ....

....The concurrent agents of SCCS must essentially pro2 ceed in lockstep and at every instant perform a single action; there is also an asynchronous operator. Since each objects in the object oriented computing proceed at indeterminate relative speeds, SCCS does not fit for our purpose. In TPA [7], timed CCS [20] and Temporal CCS [13] delay operators are introduced into CCS. The delay operators represent the suspension of execution for a specified time, similar to the delay command in Ada. In TPA and timed CCS, the authors assume, like us, that time proceeds if any communications are ....

Hennessy,M. and Regan,T., A Temporal Process Algebra, Technical Report 2/90, University of Sussex, 1990

.... [HaJ 90, Han 91] New process algebras have been proposed which are intended to model time in a quantitative way: first, synchronous process algebras such as SCCS [Mil 83] Meije [AuB 85] or CIRCAL [Mil 85] and, in a second step, timed process algebras such as TPL (Temporal Process Language) HeR 90] ATP (Algebra of Timed Processes) NRS 90, NS 90, NSY 91] PADS (Process Algebra for Distributed Systems) Azc 90] An overview and synthesis on Timed Process Algebras may be found in [NS 91] In this paper, we present a timed extension of LOTOS, denoted TLOTOS, with the objective of upward ....

....as much as possible its use by those who were trained on standard LOTOS. These are our requirements for claiming (true) upward compatibility. They will be further developed in section 2. An upward compatible timed extension to LOTOS 218 TLOTOS has been inspired by other approaches such as TPL [HeR 90] ATP [NS 90] ACP t te [Gro 90] and PADS [Azc 90] Our model is between a strictly asynchronous algebra (like LOTOS, CCS, CSP, ACP) and a strictly synchronous one (like SCCS, CIRCAL, Meije) The idea has been suggested in the works previously mentioned here above and may be informally ....

[Article contains additional citation context not shown here]

M. Hennessy, T. Regan, A temporal process algebra, in: J. Quemada, J. Maas, E. Vazquez, eds., FORTE '90, Madrid, Spain, Nov. 90 (to be published by North-Holland, Amsterdam, 1991).

.... TIC [QAF 90] TiCCS (Timed CCS) Wan 90, Wan 91] TiCSP (Timed CSP) ReR 88, Ree 90] Timed arc PN [Wal 83] Timed PN [MeF 76] TinLOTOS (TimedInteraction LOTOS) BLT 90] TLOTOS [Led 92] Timed LOTOS [LeL 92] ULOTOS T LOTOS [BoL 92] TPCCS [Haj 90, Han 91] TPL (Temporal Process Language) HeR 91] As we can see, there exist many proposals, and interesting novelties appear regularly. This situation reflects the diversity of the philosophies envisaged about the way time should be introduced in the FDTs, and the variety of the options explored in order to realize them. An overview and ....

M. Hennessy, T. Regan, A temporal process algebra, in: J. Quemada, J. Maas, E. Vazquez, eds., Formal Description Techniques III, (North-Holland, Amsterdam, 1991) 33-48.

.... Systems) Azc 90] TCCS (Temporal CCS) MoT 90] TIC [QAF 89] Timed CCS [Wan 90, Wan 91] Timed CSP [ReR 88, DaS 89, Ree 90] Timed interaction LOTOS [BLT 90] TLOTOS [Led 92] T LOTOS and ULOTOS [BoL 92] TPCCS (Timed Probabilistic CCS) HaJ 90, Han 91] TPL (Temporal Process Language) HeR 90] An overview and synthesis on Timed Process Algebras may be found in [NiS 91a] The time extended version of LOTOS that we propose in this paper for the modelling of quantitative timed behaviours has been inspired by some of the above mentioned languages, and will be compared to them as often ....

M. Hennessy, T. Regan, A temporal process algebra, in: J. Quemada, J. Maas, E. Vazquez, eds., Formal Description Techniques, III (North-Holland, Amsterdam, 1991) 33-48.

....[13] Many theoretical models for real time computations have been explored in temporal logic, timed Petri nets, and denotational semantics frameworks based on linear history semantics. More recently, several studies developed temporal models based on process calculi such as CCS, ACP, and CSP [6, 5, 10, 16, 14, 23]. Milner s SCCS [10] is a calculus for synchronous processes based on the idea that each atomic action takes one unit of time. The concurrent agents of SCCS essentially proceed in lockstep and at every instant perform a single action; there is also an asynchronous operator. Since each object in an ....

....one unit of time. The concurrent agents of SCCS essentially proceed in lockstep and at every instant perform a single action; there is also an asynchronous operator. Since each object in an object oriented computation proceeds at indeterminate relative speeds, SCCS does not fit our purposes. TPA [6], timed CCS [23] and Temporal CCS [14] introduce delay operators into CCS. The delay operators represent the suspension of execution for a specified time, similarly to the delay command in Ada. In TPA and timed CCS, like in RtCCS, there are two assumptions: time advances only when communications ....

Hennessy, M. and Regan, T., A Temporal Process Algebra, Technical Report 2/90, University of Sussex, 1990

.... Network Process Process Process Black Box Figure 1: Netted Processes For our purpose we need a way how to express also a duration of actions (communications) For this we use a simple timed model of a process algebra capable of expressing the duration of actions. Among many timed models [HR90], MT90] Gr90b] GMS91] Yi91] we choose 2 TiCCS, a slight modification of the one in [GMS91] which seems to be fully suitable. We take a CCS process and then, with the help of a time refinement, we model the duration of actions. The main idea of TiCCS is to introduce an auxiliary action t ....

....does not consider limitations imposed by physical architecture. Moreover every timed calculus has to deal with communications. If it allows idling to elementary actions then there is problem whether also an internal action may idle. The usual solution is that of restricting idling for (see [HR90], Yi91] It is based on an idea that an environment has no influence on performing any internal actions and so there is no reason for idling. A possible background of this assumption is such that if two processes can communicate than they will communicate immediately, i.e. there is always a free ....

[Article contains additional citation context not shown here]

M. Hennessy and T. Regan. A Temporal Process Algebra. In FORTE '90, Third International Conference on Formal Description Techniques, Madrid, November 5-8, pp. 25-40, 1990.

....and therefore the communication is possible only if there is free link in a net. For our purpose we need a way how to model also a duration of actions (communications) For this we use a simple timed model of a process algebra capable of expressing duration of actions. Among many timed models [HR90], MT90] Gr90b] GMS91] Yi91] we choose TiCCS, a slight modification of the one in [GMS91] which seems to be fully suitable. The main idea of TiCCS is to introduce a t action into a standard process algebra, such as CCS. The execution of a t action by a process indicates that the process is ....

....takes into account properties of an interconnection communication network. Every timed calculus has to deal with communications. If it allows idling to elementary actions then there is problem whether also an internal action may idle. The usual solution is that of restricting idling for (see [HR90], Yi91] It is based on an idea that an environment has no influence on performing any internal actions and so there is no reason for idling. A possible background of this assumption is that if two processes can communicate than they will communicate immediately, i.e. there is always a free link ....

[Article contains additional citation context not shown here]

M. Hennessy and T. Regan. A Temporal Process Algebra. In FORTE '90, Third International Conference on Formal Description Techniques, Madrid, November 5-8, pp. 25-40, 1990. 16

....of a combination of CCS (for prefixing and recursion) and ACP (for ffi, choice, parallel and encapsulation) with a unique feature, the unit delay operator. In the following presentation, the classification criterion is the standard algebra extended. 7. 1 Extensions of CCS Hennesy and Regan [HR90] present a process algebra TPL, which is an extension of CCS with a time action oe, playing the role of in ATP. An important difference with our model is that non internal actions a other than oe may be delayed (a:t oe a:t) The maximal progress assumption is adopted in TPL, that is, pjq may ....

....the same sequence from p is N iljb:N il, and the processes N iljoe:b:N il and N iljb:N il are not equivalent. Thus, it is not possible to have a law such as the expansion theorem. Yi [Wan90] describes another extension of CCS, called TCCS (Timed CCS) which is very close to the proposal of [HR90], in the sense that the process ff:P can let time pass before executing ff, whereas :P cannot. The important difference is that this work deals with continuous time; therefore a set of time events ffl(t) where t is a positive real number) is considered, rather than a time action. The process ....

[Article contains additional citation context not shown here]

M. Hennessy and T. Regan. A Temporal Process Algebra. Technical Report 2/90, University of Sussex, April 1990.

....widely in specifying and verifying concurrent systems. To expand their usefulness to real time systems, several real time process algebras have been developed by adding the notion of time and including a set of timing operators; e.g. Baeten and Bergstra (1991,1992) Davies and Schneider (1995) Hennessy and Regan (1990,1995) Moller and Tofts (1990) Nicollin and Sifakis (1994) Reed and Roscoe (1987) and Yi (1991) The most salient aspect of process algebras is that they support the modular specification and verification of a system. This is due to the algebraic laws that form a compositional proof system, ....

....developed a set of laws complete for finite processes. This paper extends the set of laws to finite state processes. We note that there are other process algebras that support the notion of priorities, including Baeten, Bergstra and Klop (1987) Camilleri and Winskel (1991) and Cleaveland and Hennessy (1990). Their approaches are overviewed and compared by Gerber and Lee (1994) The rest of the paper is organized as follows. In Section 2, we briefly introduce the computation model. In Section 3, we present the syntax of the algebra and describe the 8 operational semantics. Section 4 defines the ....

Hennessy, M., and Regan, T. (1990), "A Temporal Process Algebra," Technical Report 2/90, Univ. of Sussex.

....on broadcasting instead of handshake. These are examples of problem areas which have motivated various adaptations and extensions of process calculi, and of other theories as well. CCS has due to its simple and elegant mathematical framework proven to be an appropriate basis for several timed [HR90, MT90, NS91, W90, W91, W91b] and probabilistic formalisms [JL91, LS88] and a new calculus based on the broadcast paradigm [Pr91, Pr93v, Pr93p] One could well say that a process calculus can favourably be used as a test bench for experiments with various adaptations, not only as a fixed formalism. An interesting and ....

Hennessy, M. and Regan, T., A Temporal Process Algebra, Technical Report 2/90, University of Sussex, 1990.

....13 3.3. Extended Timed Modal Logic 16 4. Conclusion and Future Work 18 References 18 DECIDING PROPERTIES OF REGULAR REAL TIMED PROCESSES 3 1. Motivation Recently, numerous models within the frameworks for timed processes based on process calculi and temporal logic have been developed [ACD90, AD90, HR90, MT90, RR86, S90, W90]. In this paper, we discuss the decidability problem associated with verifying properties of processes expressed in the real time process calculus TCCS of Wang [W90] As the specification language for expressing such properties one may choose to use the timed calculus itself, with the notion of ....

.... [W90] As the specification language for expressing such properties one may choose to use the timed calculus itself, with the notion of correctness given in terms of some time sensitive abstracting equivalence (a timed version of bisimulation equivalence, say) In a discrete timed model such as [S90, HR90], only one unique time event is introduced into the untimed model of CCS [M89] to deal with timing information, which represents a clock tick. In these models the addition of time does not contribute to the infiniteness of the labelled transition system in terms of which the the operational ....

M. Hennessy and T. Regan, A Temporal Process Algebra, Technical Report 2/90, University of Sussex, 1990.

....of tasks that compete for shared resources. Most current real time formalisms adequately capture delays due to component synchronization, e.g. Statecharts [10] Modechart [18] Communicating Real time State Machine [32] and timed extensions of the classic untimed process algebras CSP and CCS [8, 15, 25, 35, 27]. These formalisms, however, abstract out resource specific details. This motivated the Communicating Shared Resources (CSR) paradigm [19, 21] to provide a formalism where the run time resource requirements of a real time system can be specified together with its functional and temporal ....

M. Hennessy and T. Regan. A Temporal Process Algebra. Technical Report 2/90, Univ. of Sussex, UK, April 1990.

....distinguishes some systems which are equivalent here. The approach of [AKH92] was recently varied in [AKN95] while [AKH92] compares the worst case as well as the best case, the new variant only takes the worst case into account (as we have done here) Faster than relations are also presented in [HR90, CZ91, MT91, CGR95]. In the first two papers, the behaviour of systems is influenced by timing considerations, i.e. the systems are not asynchronous. In [MT91] also a bisimulation type preorder is defined and actions are regarded as instantaneous; a unit time delay operator with a special treatment is introduced, ....

....i.e. the systems are not asynchronous. In [MT91] also a bisimulation type preorder is defined and actions are regarded as instantaneous; a unit time delay operator with a special treatment is introduced, which makes the comparison to our approach very difficult. Such an operator is also used in [HR90], where a testing scenario is developed based on the maximal progress assumption, which is suitable for synchronous systems. Time consuming actions are considered in [CZ91, CGR95] a testing approach is presented in [CZ91] where the systems and tests under consideration have to be restricted to ....

M. Hennessy and T. Regan. A temporal process algebra. Technical Report 2/90, Dept. Comp. Sci. Univ. of Sussex, Brighton, 1990.

....[13] Many theoretical models for real time computations have been explored in temporal logic, timed Petri nets, and denotational semantics frameworks based on linear history semantics. More recently, several studies developed temporal models based on process calculi such as CCS, ACP, and CSP [6, 5, 10, 16, 14, 23]. Milner s SCCS [10] is a calculus for synchronous processes based on the idea that each atomic action takes one unit of time. The concurrent agents of SCCS essentially proceed in lockstep and at every instant perform a single action; there is also an asynchronous operator. Since each object in an ....

....one unit of time. The concurrent agents of SCCS essentially proceed in lockstep and at every instant perform a single action; there is also an asynchronous operator. Since each object in an object oriented computation proceeds at indeterminate relative speeds, SCCS does not fit our purposes. TPA [6], timed CCS [23] and Temporal CCS [14] introduce delay operators into CCS. The delay operators represent the suspension of execution for a specified time, similarly to the delay command in Ada. In TPA and timed CCS, like in RtCCS, there are two assumptions: time advances only when communications ....

Hennessy, M. and Regan, T., A Temporal Process Algebra, Technical Report 2/90, University of Sussex, 1990

....our first preorder is essentially that of [7] Finally, we mention also a temporal model based on continuous time [15] where higher order transitions and computations are given a geometric description. Temporal extensions of process algebra not directly related to our proposal may be found in [23, 24, 3, 21, 16, 17, 18]. A survey of these approaches can be found in [22] Many other models for timed behaviours have been proposed in the literature, e.g. those based on Kripke structures, automata, temporal logics. We do not discuss them here and we refer the interested reader to for instance the proceedings of ....

M. Hennessy and T. Regan. A temporal process algebra. Technical Report 2/90, University of Sussex, 1990.

....that facilitates description of concurrent real time systems with finite supplies of serially reusable resources. Most current real time process algebras adequately capture delays due to process synchronization, e.g. timed extensions of the classic untimed process algebras CSP and CCS [1] 11] [16], 23] 24] 29] These process algebras, however, abstract out resource specific details. In contrast, the computation model of ACSR is based on the view that a real time system consists of a set of communicating processes that compete for shared resources. The use of shared resources is ....

M. Hennessy and T. Regan. A Temporal Process Algebra. Technical Report 2/90, Univ. of Sussex, UK, April 1990.

....means that a process may stay in the same state for one unit of time and then move to another state by synchronizing with the global clock tick. The assumption has been adopted by various synchronous real time programming languages like Esterel, BC83] and discrete time process algebras like ATP, [HR91] [HJ91] J91] S90] 1 The symbol has been used for a similar purpose in the timed algebra, ATP by Sifakis et al. 3 ae oe ae oe ae oe ae oe Gamma Gamma Gamma Gamma Psi R [0:9; 1] 0; 0:1] ff P 2 P 1 Q P Figure 1: A real time probabilistic process with uncertain ....

....internal actions are independent of the environment and therefore, they are represented by the distinct symbol . As said earlier, internal actions are independent of the environment and therefore, transitions are autonomous. We shall follow another assumption from timed models, RR86] RH89] [HR91] [HJ91] J91] W91] That is, transitions labeled by internal actions (or ) will be performed as soon as they are enabled. This assumption is also known as maximal progress or maximal parallelism. It means that a process must proceed whenever it can do so. 4 2.2 Timed Probabilistic ....

[Article contains additional citation context not shown here]

M. Hennessy and T. Regan, A Temporal Process Algebra, Technical Report 5/91, University of Sussex, 1991.

....transformation of mapping an initial design for a system onto an actual implementation with jobs scheduled on processors. 1 Introduction Many formalisms exist for designing and verifying real time systems, for example, TAM [SZ92, SZJ93, SZ93] Timed CSP [RR86, DS92, DRRS94] and Timed CCS [MT90, Yi90, HR90]. However, none of these formalisms have dealt with the important problems of resource allocation and scheduling. The formalisms have adopted the unbounded parallelism hypothesis, i.e. the assumption that sufficient resources are always available. However, implementations of real time systems ....

M. Hennessy and T. Regan. A temporal process algebra. Technical Report 2-90, University of Sussex, 1990.

....to specify, design and schedule a program that controls part of the start up of an aircraft engine. 1 Introduction Many formalisms exist for specifying, designing and verifying real time systems, for example, the Temporal Agent Model (TAM) SZ92, SZJ94] Timed CSP [DS94, DRRS94] and Timed CCS [HR90, MT90, Yi90]. However, these formalisms have not dealt with the important problems of resource allocation and scheduling. The formalisms have adopted the unbounded parallelism hypothesis, i.e. that sufficient resources are always available. However, in real systems this is rarely true. In [Low94] I developed ....

M. Hennessy and T. Regan. A temporal process algebra. Technical Report 2-90, University of Sussex, 1990.

....can see the passage to the next time slice as a clock tick. Thus, the cts(a) can be called non delayable actions: the action must occur before the next clock tick. The operators are alternative and sequential composition, and the relative discrete time unit delay # rel (the notation # taken from [17]) The process # rel (x) will start x after one clock tick, i.e. in the next time slice. In addition, we add the auxiliary operator # rel . This operator, called the current slice time out operator, or current slice operator in short, disallows an initial time step, it gives the part of a process ....

M. Hennessy and T. Regan. A temporal process algebra. Technical Report 2/90, University of Sussex, 1990.

....SZ92, SZ93] a wide spectrum development language for real time systems, with constructs for such features as communication, deadline and parallelism. It is possible to reason about resource allocation in event based process algebras, such as Timed CSP [RR86, DS95, DRRS95] or timed versions of CCS [MT90, Yi90, HR90], by modelling resources as processes. This approach can work well when the program itself is easily modelled as a process; however, eventbased process algebras tend to have a very different syntax to most traditional programming languages, so this modelling can be somewhat unnatural. In such ....

M. Hennessy and T. Regan. A temporal process algebra. Technical Report 2-90, University of Sussex, 1990.

....sensitive, our first preorder is essentially that of [7] Finally, we mention also a temporal model based on continuous time [15] where higher order transitions and computations are given a geometric description. Temporal extension of process algebra not directly related to our proposal are [21, 22, 3, 19, 16]. A survey of these approaches can be found in [20] Many other models for timed behaviours have been proposed in the literature, e.g. those based on Kripke structures, automata, temporal logics. We do not discuss them here and we refer the interested reader for instance to the proceedings of ....

M. Hennessy and T. Regan. A temporal process algebra. Technical Report 2/90, University of Sussex, 1990.

....and a grant from ETRI. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Air Force Office of Scientific Research or the U.S. Government. and CCS [3, 4, 6, 11, 13, 12]. These formalisms, however, abstract out resource specific details. This motivated the Communicating Shared Resources (CSR) paradigm [8, 9] to provide a formalism where the runtime resource requirements of a real time system can be specified together with its functional and temporal requirements. ....

M. Hennessy and T. Regan. A Temporal Process Algebra. Technical Report 2/90, Univ. of Sussex, UK, April 1990.

....all internal events to be urgent. This leads to similar problems between urgency and causality as reported in [49] Timed process algebras In the last decade timed extensions of process algebras have received considerable attention. Extensions of languages like ACP [3] CSP [71, 75] CCS [36, 59, 82, 38], and LOTOS [9, 54, 70] have been defined. For an overview of the issues that arise when adding time to process algebras we refer to [64] In this paper we showed how the benefits of event structures can be exploited when having a time prefix specifying at which times an action may occur and using ....

....how the benefits of event structures can be exploited when having a time prefix specifying at which times an action may occur and using urgency only for modelling timeout scenarios. Most approaches differ in the way urgency is approached. 3] forces each action to happen as soon as possible, [38, 75, 54], for instance, adopt this strategy for internal actions only, and, in the most extreme case, an operator is introduced that allows any action to be interpreted in an urgent way or not [9] In [49] we showed that the latter strategy leads to an undesirable connection between causality and urgency. ....

M. Hennessy and T. Regan. A temporal process algebra. Inf. & Comp., 117:221--239, 1995.

....of inequations. Recall that the proof rule Summand Elimination is essential to our proof system. There has been much recent work on introducing notions of time into process algebras. 3] and [12] are typical examples of one approach, where real time durations are associated with actions. 11] and [8] are examples of another approach where actions are still instantaneous but a special action is introduced to represent the passage of time. Neither of these approaches is directly comparable with the one presented here, which we believe to be the first improvement preorder based on time. There ....

M. Hennessy and T. Regan. A temporal process algebra. Technical Report, 2/90, University of Sussex, 1990.

No context found.

M. Hennessy and T. Regan. A Temporal Process Algebra. In FORTE '90, Third International Conference on Formal Description Techniques, Madrid, November 5-8, pp. 25-40, 1990. 16

No context found.

M. Hennessy and T. Regan. A Temporal Process Algebra. In FORTE '90, Third International Conference on Formal Description Techniques, Madrid, November 5-8, 1990, pp. 25-40, 1990.

No context found.

M. Hennessy and T. Regan. A Temporal Process Algebra. In FORTE '90, Third International Conference on Formal Description Techniques, Madrid, November 5-8, pp. 25-40, 1990.

No context found.

M. Hennessy and T. Regan. A Temporal Process Algebra. Technical Report, University of Sussex (UK), 1990.

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