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ERRATA: Paper [EndrissAAMAS2006]
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U. Endriss.
Monotonic Concession Protocols for Multilateral Negotiation.
Proc. 5th International Conference on Autonomous Agents and Multiagent
Systems (AAMAS-2006), pages 392-399, ACM Press, May 2006.
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In the proof of Proposition 3, the counterexample given to show that Pareto 
concessions, supposedly, are not deadlock-free is wrong. To see this, 
observe that agent 3 can make a Pareto concession by moving from agreement 
x_3 to agreement x_1.

Whether Pareto concessions in fact are deadlock-free is an open problem.

Note that the claim that strong concessions are not deadlock-free is still 
correct. In particular, agent 3 moving from agreement x_3 to agreement x_1 
is not a strong concession.

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