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A theory of agreements and protection

posted Dec 17, 2012, 1:48 AM by Massimo Bartoletti   [ updated Dec 17, 2012, 1:49 AM ]
Upcoming paper (to be presented at POST 2013, Rome, Mar 16-24 2013)

A theory of agreements and protection

M. Bartoletti, T. Cimoli and R. Zunino

We present a theory of contracts. Contracts are interacting processes with an explicit notion of obligations and objectives. We model processes and their obligations as event structures. We define a general notion of agreement, by interpreting contracts as multi-player concurrent games. A participant agrees on a contract if she has a strategy to reach her objectives (or make another participant chargeable for a violation), whatever the moves of her adversaries.

We then tackle the problem of protection. A participant is protected by a contract when she has a strategy to defend herself in all possible contexts, even in those where she has not reached an agreement. We show that, in a relevant class of contracts, agreements and protection mutually exclude each other.

We then propose a novel formalism for modelling contractual obligations: event structures with circular causality. Using this model, we show how to construct contracts which guarantee both agreements and protection.