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A Calculus of Broadcasting Systems
 SCIENCE OF COMPUTER PROGRAMMING
, 1991
"... CBS is a simple and natural CCSlike calculus where processes speak one at a time and are heard instantaneously by all others. Speech is autonomous, contention between speakers being resolved nondeterministically, but hearing only happens when someone else speaks. Observationally meaningful laws dif ..."
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Cited by 62 (8 self)
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CBS is a simple and natural CCSlike calculus where processes speak one at a time and are heard instantaneously by all others. Speech is autonomous, contention between speakers being resolved nondeterministically, but hearing only happens when someone else speaks. Observationally meaningful laws differ from those of CCS. The change from handshake communication in CCS to broadcast in CBS permits several advances. (1) Priority, which attaches only to autonomous actions, is simply added to CBS in contrast to CCS, where such actions are the result of communication. (2) A CBS simulator runs a process by returning a list of values it broadcasts. This permits a powerful combination, CBS with the host language. It yields several elegant algorithms. Only processes with a unique response to each input are needed in practice, so weak bisimulation is a congruence. (3) CBS subsystems are interfaced by translators; by mapping messages to silence, these can restrict hearing and hide speech. Reversi...
Programming With Broadcasts
 In CONCUR
, 1993
"... . [Pra91, Pra92] develop CBS, a CCSlike calculus [Mil89] where processes communicate by broadcasting values along a single channel. These values are hidden or restricted by translation to noise. This paper types CBS and restricts it to processes with a unique response to each input. Nondeterminism ..."
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Cited by 20 (7 self)
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. [Pra91, Pra92] develop CBS, a CCSlike calculus [Mil89] where processes communicate by broadcasting values along a single channel. These values are hidden or restricted by translation to noise. This paper types CBS and restricts it to processes with a unique response to each input. Nondeterminism arises only if two processes in parallel both wish to transmit. These restrictions do not reduce the programming power of CBS. But strong and weak bisimulation can now be defined exactly as in CCS, yet capture observationally meaningful relations. Weak bisimulation is a congruence. This paper also shows how to program in CBS in a (lazy) ML framework. A simple CBS simulator is given, and a parallel implementation discussed. The simulator represents data evaluation, recursion and conditionals directly in Lazy ML. It implements an extended CBS with evaluation as well as communication transitions. [Pra91, Pra92] develop a CCSlike [Mil89] calculus of broadcasting systems, CBS. This paper continu...
A Calculus Of Value Broadcasts
 IN PARLE'93
, 1993
"... Computation can be modelled as a sequence of values, each broadcast by one agent and instantaneously audible to all those in parallel with it. Listening agents receive the value; others lose it. Subsystems interface via translators; these can scramble values and thus hide or restrict them. Examples ..."
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Cited by 17 (5 self)
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Computation can be modelled as a sequence of values, each broadcast by one agent and instantaneously audible to all those in parallel with it. Listening agents receive the value; others lose it. Subsystems interface via translators; these can scramble values and thus hide or restrict them. Examples show the calculus describing this model to be a powerful and natural programming tool. Weak bisimulation, a candidate for observational equivalence, is defined on the basis that receiving a value can be matched by losing it.
Broadcasting in Time
"... . In the calculus of broadcasting systems (CBS), speech is autonomous, but hearing takes place only when the environment speaks. This paper develops a timed CBS (TCBS) where no time may pass if there is speech pending. A process wishing to speak can be forced, by attaching a timeout to it, to first ..."
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Cited by 6 (3 self)
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. In the calculus of broadcasting systems (CBS), speech is autonomous, but hearing takes place only when the environment speaks. This paper develops a timed CBS (TCBS) where no time may pass if there is speech pending. A process wishing to speak can be forced, by attaching a timeout to it, to first listen for a specified length of time. TCBS subsumes CBS with priorities, and has an expansion theorem even if time is dense. A delay prefix operator can be derived up to weak bisimulation. TCBS casts light on issues in handshake communication: time abstracted bisimulation, and the relations between time and priority, between expansion theorems and density of time, and between delays and timeouts. 1 Introduction Background A plethora of timed process calculi now exist, and a tutorial, [Hen92], notes that there is very little difference between untimed and timed languages. Current research has moved away from the setting up of timed calculi, and focussed on more esoteric issues such as the ...
Status report on ongoing work: Higher Order Broadcasting Systems (HOBS) and Reasoning about Broadcasts
, 1994
"... re is firstly to study convenient programming with HOBS, rather than to treat it as a primitive from which the calculus can be derived. ? Funding: From the Swedish Government agencies TFR and NUTEK, the latter supporting Chalmers' membership of the Esprit Basic Research Action CONCUR2 The basic ..."
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Cited by 3 (2 self)
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re is firstly to study convenient programming with HOBS, rather than to treat it as a primitive from which the calculus can be derived. ? Funding: From the Swedish Government agencies TFR and NUTEK, the latter supporting Chalmers' membership of the Esprit Basic Research Action CONCUR2 The basic ideas are as follows. The type of a process can be thought of as the language it speaks. Thus processes speak Bool, Char, or indeed English or Swedish. Let Swedish be the language of the environment. Then if E: : Proc English is an English speaking process it can be integrated into an Swedish speaking environment by placing it in the scope of a translator OE j hOE " ; OE # i where OE " : : English ! Swedish and OE " : : Swedish ! English.
A Machine Verified Distributed Sorting Algorithm
 ABSTRACT APPEARED IN 7TH NORDIC WORKSHOP ON PROGRAMMING THEORY, NWPT '7 PROCEEDINGS
, 1996
"... We present a verification of a distributed sorting algorithm in ALF, an implementation of Martin Löf's type theory. The implementation is expressed as a program in a priortized version of CBS, (the Calculus of Broadcasting Systems) which we have implemented in ALF. The specification is expressed ..."
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Cited by 2 (0 self)
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We present a verification of a distributed sorting algorithm in ALF, an implementation of Martin Löf's type theory. The implementation is expressed as a program in a priortized version of CBS, (the Calculus of Broadcasting Systems) which we have implemented in ALF. The specification is expressed in terms of an ALF type which represents the set of all sorted lists and an HML (HenneseyMilner Logic) formula which expresses that the sorting program will input any number of data until it hears a value triggering the program to begin outputting the data in a sorted fashion. We gain expressive power from the type theory by inheriting the language of data, state expressions, and propositions.
Negative premises in applied process calculi
"... Abstract. We explore two applications of negative premises to increase the expressive power of psicalculi: reliable broadcasts and priorities. Together, these can be used to model discrete time, and we illustrate with an example from automotive applications. The negative premises can be encoded by ..."
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Abstract. We explore two applications of negative premises to increase the expressive power of psicalculi: reliable broadcasts and priorities. Together, these can be used to model discrete time, and we illustrate with an example from automotive applications. The negative premises can be encoded by a twolevel structural operational semantics without negative premises; we use this fact to prove the standard congruence and structural laws of bisimulation with Nominal Isabelle. 1