General mathematical model of incomplete contracts?

Question

I have read various articles about incomplete contracts, like Hart's papers and Milgrom's papers.

But I have not found a paper that defines mathematically, in the most general way possible, what an contract is, and how a contract can be more, or less, "incomplete".

Is there a general model that has as special cases the incomplete contracts studied in the literature (e.g. by Hart, Incomplete Contracts and the Theory of the Firm, and others), and perhaps also as special case the complete contracts?

Note: I am not necessarily asking for a general model that can include all the reasons for incomplete contracts (thought that would be nice too). Just a model that can be used to state how (in)complete a particular contract is, whatever the reason.

Answer 1

Just a model that can be used to state how (in)complete a particular contract is, whatever the reason.

• I remember a debate at the end of the 90's on Incomplete Contracts: Where do We Stand? by Jean Tirole and Foundations of Incomplete Contracts by Hart and Moore, where they develop a model that provides a rigorous foundation for the idea that contracts are incomplete, followed by Complexity and Renegotiation: A Foundation for Incomplete Contracts by Segal.
• Check also this book The Impact of Incomplete Contracts on Economics (2006) by Aghion, Dewatripont, Legros, and Zingales, including Comments on the Foundations of Incomplete Contracts by Maskin.
• An interesting paper by Tirole Cognition and Incomplete Contracts: Thinking about contingencies, designing covenants, and seeing through their implications is costly. Parties to a contract accordingly use heuristics and leave it incomplete. The paper develops a model of limited cognition and examines its consequences for contractual design.