## An Asynchronous Process Algebra with Multiple Clocks (1994)

Venue: | ESOP'94. Proceedings of the 5th European Symposium on Programming |

Citations: | 26 - 8 self |

### BibTeX

@INPROCEEDINGS{Andersen94anasynchronous,

author = {Henrik Reif Andersen and Michael Mendler},

title = {An Asynchronous Process Algebra with Multiple Clocks},

booktitle = {ESOP'94. Proceedings of the 5th European Symposium on Programming},

year = {1994},

pages = {58--73},

publisher = {Springer-Verlag}

}

### Years of Citing Articles

### OpenURL

### Abstract

. In this paper we introduce a novel approach to the specification of real-time behaviour with process algebras. In contrast to the usual pattern, involving a fixed, measurable, and global notion of time, we suggest to represent real-time constraints indirectly through uninterpreted clocks enforcing broadcast synchronization between processes. Our approach advocates the use of asynchronous process algebras, which admit the faithful representation of nondeterministic and distributed computations. Technically, we present a non-trivial extension of the Calculus of Communicating Systems CCS [Mil89a] by multiple clocks with associated timeout and clock ignore operators. We illustrate the flexibility of the proposed process algebra, called PMC , by presenting examples of rather different nature. The timeout operators generalize the timeout of ATP [NS90] to multiple clocks. The main technical contribution is a complete axiomatization of strong bisimulation equivalence for a class of finite-s...

### Citations

3204 |
Communication and Concurrency
- Milner
- 1989
(Show Context)
Citation Context ...rocess algebras, which admit the faithful representation of nondeterministic and distributed computations. Technically, we present a non-trivial extension of the Calculus of Communicating Systems CCS =-=[Mil89a]-=- by multiple clocks with associated timeout and clock ignore operators. We illustrate the flexibility of the proposed process algebra, called PMC , by presenting examples of rather different nature. T... |

1967 | A Theory of Timed Automata
- Alur, Dill
- 1994
(Show Context)
Citation Context ...ion of `clock'. For most purposes this term would denote a means for measuring time in order to time-stamp observations. In the process language CIPA [AM93a] or in the timed automata of Alur and Dill =-=[AD91]-=- clocks are used in this sense. In PMC, however, the intended interpretation of `clock' is more like that of a hardware clock, viz. a global signal used to synchronize asynchronous computations in a l... |

172 |
A temporal calculus of communicating systems
- Moller, Tofts
- 1990
(Show Context)
Citation Context ...ion of t which allows oe to proceed until such time as the environment is ready to communicate with it. These constructs are taken as primitives in the timed process calculus TCCS of Moller and Tofts =-=[MT90]-=-. In [MT92] a complete axiomatization for TCCS of observation congruence on finite, sequential processes is presented. Both PMC and TCCS use insistent action prefixes, but where PMC has a timeout oper... |

140 | An overview and synthesis on timed process algebras
- Nicollin, Sifakis
- 1992
(Show Context)
Citation Context ...troduction According to consolidating tradition in timed process algebras a real-time system is perceived to operate under the regime of a global time parameter constraining the occurrence of actions =-=[NS91b]-=-. Time has algebraic structure, typically a totally ordered commutative monoid, to express quantitative timing constraints. The semantics of a timed process then is given as a transition system enrich... |

122 | A complete inference system for a class of regular behaviours - Milner - 1984 |

105 | The algebra of timed processes ATP: theory and application
- Nicollin, Sifakis, et al.
- 1994
(Show Context)
Citation Context ...ck ignore operators. We illustrate the flexibility of the proposed process algebra, called PMC , by presenting examples of rather different nature. The timeout operators generalize the timeout of ATP =-=[NS90]-=- to multiple clocks. The main technical contribution is a complete axiomatization of strong bisimulation equivalence for a class of finite-state processes and a complete axiomatization of observation ... |

91 |
The Esterel synchronous programming language and its mathematical semantics
- Berry, Cosserat
- 1985
(Show Context)
Citation Context ...ns. Lustre was developed originally for real-time programming but is used also for describing digital circuits. Another quite successful real-time language with a multi-form notion of time is Esterel =-=[BC84]-=-. It must be noted however, that in both these languages clocks are not built-in; they are ordinary signals or variables, not an independent semantical concept as in PMC. A synchronous language where ... |

80 | From ATP to Timed Graphs and Hybrid Systems
- Nicollin, Yovine
- 1991
(Show Context)
Citation Context ...ebras require to give exact numbers for the duration of actions, such as "3:141 time units to enter a valid login response". Examples are Timed-ACP as described in [Klu91], Timed-CSP [SDJ + =-=91], ATPD [NS91a]-=-, or [Wan90]. But exact delays are in general very difficult to implement due to uncontrollable fabrication parameters, operating conditions such as circuit temperature or external events. At best we ... |

61 | Real-time behaviour of asynchronous agents - Yi - 1990 |

57 |
A complete axiomatisation for observational congruence of finitestate behaviours
- Milner
- 1989
(Show Context)
Citation Context ...t quite so simple. There are some subtle technical complications making PMC a non-trivial extension of CCS. Firstly, the standard approach extending completeness from finite to finite-state processes =-=[Mil89b]-=- builds on the fact that in CCS unguarded processes can always be transformed into guarded ones. Unfortunately, this property fails to hold for PMC, with the consequence ifsc can be completely axiomat... |

42 |
Real-time behaviour of asynchronous agents. CONCUR ’90 Theories of Concurrency: Unification and Extension
- Wang
- 1990
(Show Context)
Citation Context ...e to give exact numbers for the duration of actions, such as "3:141 time units to enter a valid login response". Examples are Timed-ACP as described in [Klu91], Timed-CSP [SDJ + 91], ATPD [N=-=S91a], or [Wan90]-=-. But exact delays are in general very difficult to implement due to uncontrollable fabrication parameters, operating conditions such as circuit temperature or external events. At best we can hope to ... |

34 | The ML Kit (Version 1
- Birkedal, Rothwell, et al.
- 1993
(Show Context)
Citation Context ...as a specification language in an industrial case study at the Department of Computer Science, DTH. A prototype implementation of a value-passing version of PMC is under development, using the ML-Kit =-=[BRTT93]-=-. Acknowledgement The authors would like to thank Anders P. Ravn, Matthew Hennessy, Gerard Berry, and Faron Moller for various comments, Anders in particular for his encouragement. Thanks are also due... |

26 | An interleaving model for real-time systems - Chen - 1992 |

23 |
On the ill-timed but well-caused
- Aceto, Murphy
- 1993
(Show Context)
Citation Context ...act time was proposed by Liang [Lia91]. Such an algebra, however, suffers even more from being cluttered up with irrelevant timing information. Another process algebra with interval durations is CIPA =-=[AM93a]-=-. A disadvantage of time intervals are the severe problems they cause for simulation, in particular where time is dense: It is not feasible faithfully to simulate time intervals for the purpose of tim... |

19 |
Timed process algebras with urgent interactions and a unique powerful binary operator, pp 124--147, LNCS 600
- Bolognesi, Lucidi
- 1992
(Show Context)
Citation Context ...ents all clocks from ticking, which motivates calling it `insistent' prefix. The term `insistent' is taken from Hennessy [Hen93]. Prefixes that stop time from progressing also have been called urgent =-=[BL91]-=- or immediate [NS91a]. Sum: t 0 + t 1 is the process which must behave as any of t 0 or t 1 , the choice being made with the first action. Composition: t 0 j t 1 represents t 0 and t 1 performing conc... |

19 |
Abstraction in real time process algebra, in
- Klusener
- 1991
(Show Context)
Citation Context ...Secondly, many real-time process algebras require to give exact numbers for the duration of actions, such as "3:141 time units to enter a valid login response". Examples are Timed-ACP as des=-=cribed in [Klu91]-=-, Timed-CSP [SDJ + 91], ATPD [NS91a], or [Wan90]. But exact delays are in general very difficult to implement due to uncontrollable fabrication parameters, operating conditions such as circuit tempera... |

12 |
On Timed Process Algebra: a Tutorial
- Hennessy
- 1993
(Show Context)
Citation Context ...nt prefix: ff:t is the process which performs ff and then behaves as t; it prevents all clocks from ticking, which motivates calling it `insistent' prefix. The term `insistent' is taken from Hennessy =-=[Hen93]-=-. Prefixes that stop time from progressing also have been called urgent [BL91] or immediate [NS91a]. Sum: t 0 + t 1 is the process which must behave as any of t 0 or t 1 , the choice being made with t... |

9 |
Behavioural abstraction in TCCS
- Moller, Torts
- 1992
(Show Context)
Citation Context ...h for the firstsactions in PMC they need to match any initial clock sequence followed by as. The third characterization coincides with one given by Moller and Tofts for observation congruence in TCCS =-=[MT92]-=-. The equivalence between the last two characterizations is due to the following property: S1 t + u = u + t S2 t + (u + v) = (t + u) + v S3 t + t = t S4 ff:t + 0 = ff:t S5 t + 1 = t B1 bbtcoe(u)coe(v)... |

8 |
Reliable High-Speed Arbitration and Synchronization
- Chapiro
- 1987
(Show Context)
Citation Context ...interconnected synchronous systems that are all driven by independent, i.e. local clocks. Such systems are called multi-clock synchronous systems or globallyasynchronous, locally-synchronous machines =-=[Cha87]-=-. The synchronous subsystems exchange data via communication buffers which decouple the computations and compensate for different relative clock speeds. The simplest case of a communication buffer is ... |

8 |
programming and verifying real-time systems using a synchronous declarative language
- Specifying
- 1990
(Show Context)
Citation Context ...ss calculi the concept of multiple synchronization clocks --- in our sense --- is novel. Yet, it is not entirely new as it has been used already in synchronous real-time description languages. Lustre =-=[HPOG89]-=- is a language for synchronous data-flow with multiple clocks, where all clocks are derived from a master clock through boolean expressions. Lustre was developed originally for real-time programming b... |

6 | Guernic, "Hybrid systems : the SIGNAL approach - Benveniste, Borgne, et al. - 1993 |

3 |
A process algebra for timed systems. Computer Science
- Hennessy, Regan
- 1991
(Show Context)
Citation Context ...m a oe time step the process p must not prevent time from progressing, which is not the case here. Examples are the constructs p d . q of Nicollin and Sifakis [NS91a] and bpc(q) of Hennessy and Regan =-=[HR91]. The rela-=-xed time behaviour of bpcoe(q) wrt. p is important for PMC as it allows us to derive from it a number of useful "time-relaxed" constructs such as relaxed prefixes. With a time-insistent time... |

3 |
An interleaving model for real-time systems
- Liang
- 1991
(Show Context)
Citation Context ...ating conditions such as circuit temperature or external events. At best we can hope to implement delay intervals. A process algebra using delay intervals rather than exact time was proposed by Liang =-=[Lia91]-=-. Such an algebra, however, suffers even more from being cluttered up with irrelevant timing information. Another process algebra with interval durations is CIPA [AM93a]. A disadvantage of time interv... |