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Subtyping and Locality in Distributed Higher Order Processes (Extended Abstract)
, 1999
"... . This paper studies one important aspect of distributed systems, locality, using a calculus of distributed higherorder processes in which not only basic values or channels, but also parameterised processes are transferred across distinct locations. An integration of the subtyping of lcalculus a ..."
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Cited by 34 (4 self)
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. This paper studies one important aspect of distributed systems, locality, using a calculus of distributed higherorder processes in which not only basic values or channels, but also parameterised processes are transferred across distinct locations. An integration of the subtyping of lcalculus and IOsubtyping of the pcalculus offers a tractable tool to control the locality of channel names in the presence of distributed higher order processes. Using a local restriction on channel capabilities together with a subtyping relation, locality is preserved during reductions even if we allow new receptors to be dynamically created by instantiation of arbitrary higherorder values and processes. We also show that our method is applicable to more general constraints, based on local and global channel capabilities. 1 Introduction There have been a number of attempts at adapting traditional process calculi, such as CCS and CSP, so as to provide support for the modelling of certain asp...
A Filter Model for Mobile Processes
 MATH. STRUCT. IN COMP. SCIENCE
, 1993
"... This paper presents a filter model for πcalculus, and shows its full abstraction with respect to a "may" operational semantics. The model is introduced in the form of a type assignment system. Types are related by a preorder which mimics the operational behaviour of terms. A subject expansion th ..."
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Cited by 7 (3 self)
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This paper presents a filter model for πcalculus, and shows its full abstraction with respect to a "may" operational semantics. The model is introduced in the form of a type assignment system. Types are related by a preorder which mimics the operational behaviour of terms. A subject expansion theorem holds. Terms are interpreted as filters of types: this interpretation is compositional. The proof of full abstraction relies on a notion of realizability of types, and on the construction of terms, which test when an arbitrary term has a fixed type.
A Minimal Calculus for Situated MultiAgent Systems
 in eProceedings, SSGRR03w (Advances in Infrastructures for eBusiness
, 2003
"... We present a processalgebraic approach to situated multiagent systems which incorporates syntax for agent systems as well as for the environments (workspaces) they live in. Agent states are characterized by (1) a belief state, (2) a goal (desire, need) state and (3) a capabilities state. Capabilit ..."
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Cited by 3 (3 self)
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We present a processalgebraic approach to situated multiagent systems which incorporates syntax for agent systems as well as for the environments (workspaces) they live in. Agent states are characterized by (1) a belief state, (2) a goal (desire, need) state and (3) a capabilities state. Capabilities are determined by a subspace of the workspace the agent lives in, and they are represented in the agent state as a collection of types of objects (tools, in the agent's workspace) the agent has the expertise (or permission) to use. Action capabilities are then just permissible transformations of workspaces, restricted to the particular capabilities space of the agent. Workspaces (certain kinds of collections of objects, modelled here as simply typed records of labelled attributes) and workspace transformations (record update operations) are structured into a transition system. We use a simple model of objects as records and, therefore, of workspaces and thus we only deal in this report with deterministic environments. Transitions are determined by agent actions (modifications of properties of objects in their capabilities space, modelled as record update operations), thus allowing for a formal account of agent systems living in an ever changing environment. Beliefs and desires are formulae of a manysorted, firstorder multimodal language of properties of workspaces, where sorts are object types and modalities are indexed by workspace transformations (record updates). The logical language is kept simple, allowing only for firstorder beliefs (beliefs about properties of workspaces). We present a language of situated, cooperative, selfinterested agent systems, proposing a basic collection of agent behaviors (including ground observation actions, commitments, communication via assertions and requests, recursive behaviors, choice, concurrent behaviors etc), we provide an operational semantics for this language and discuss some examples of useful definable agent behaviors, such as perceiving (performing observations triggered by a statement). We then present and discuss notions of (behavioral) agent preorder and equivalence relations. Using the operational semantics and our notion of behavioral preorder and equivalence we propose an inequational theory for reasoning about agents. We conclude with presenting and discussing a case study for a simple agent system.
Denotational Semantics for a HigherOrder Extension of the Monadic \pi Calculus (draft paper)
"... We study a version of the higherorder #calculus where transmittable items include items of ground type, such as communication channel names, but functions into processes as well. After providing operational semantics to the language we lay out a basic equational theory # which includes interleavin ..."
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Cited by 2 (0 self)
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We study a version of the higherorder #calculus where transmittable items include items of ground type, such as communication channel names, but functions into processes as well. After providing operational semantics to the language we lay out a basic equational theory # which includes interleaving and normal form laws. We then construct a denotational model by solving an appropriate domain equation in a functor category. We provide explicit constructions of the syntactic operators and demonstrate (1) that the equational theory # presented is valid in the model. Finally, (2) we derive from validity of # a Computational Adequacy Theorem for the model. 1 Preliminaries Interest in recent years has clearly turned to languages for describing distributed systems as well as to languages with higherorder features and languages incorporating both functional and concurrent features. Relevant work includes, among others, CML [16], the #calculus [14], the Join Calculus [7], and Facile [5]. La...