Introduction to Pos: A Protocol Operational Semantics

Abstract

In this paper, we propose a system for representing interaction protocols called POS which is both Turing complete and determine a complete semantics of protocols. This work is inspired by the Structured Operational Semantics in programming languages. We precisely define POS and illustrate its power on an extended example.

Modeling interaction strategies using POS: An application to soccer robots

“…In a more theoretical and technical paper [20] we have presented the Protocol Operational Semantics (POS), an interaction protocol model based on abstract data-types and pattern matching capabilities. Endowed with these special features, POS has a high expressive power which generally makes it an interesting approach for coordinating agents in multiagent systems.…”

“…POS is a general interaction protocol/conversation policies engineering formalism and was proved to be efficient for the design of communities of software information agents [20]. We will show here that it is also valuable for robotic agents that have to operate in real time, like in the case of robot-soccer.…”

“…In a theoretical paper [20] we have extensively developed the POS model. This current section briefly summarizes its main characteristics.…”

“…First, while in expert systems productions rules are used to design the reasoning system of one (autistic) expert, this is mainly used here to coordinate the reasoning of a team of experts and incorporate a messaging dimension into the rules. Second, premises are not only a test over some aspect of the world, but include a patterned state which allows to code compactly arbitrarily sophisticated sequences of operations [20].…”

“…Using finite state automata most often amounts to adding "enormous numbers of little used error handling transitions, often to the extent that the preferred conversational flow in the net is completely obscured" [11], whereas with POS rules resembling (6) can do the job elegantly. In a general framework, because POS is a calculus model with universal power [20], many protocols or constraints over conversations can be expressed in POS but simply cannot be described by finite state machines or Petri nets without serious extensions.…”