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On the complexity of the Shapley-Scarf economy with several types of goods. (English) Zbl 1200.91027
Summary: In the Shapley-Scarf economy each agent is endowed with one unit of an indivisible good (house) and wants to exchange it for another, possibly the most preferred one among the houses in the market. In this economy, core is always nonempty and a core allocation can be found by the famous Top Trading Cycles algorithm. Recently, a modification of this economy, containing $$Q \geq 2$$ types of goods (say, houses and cars for $$Q=2$$) has been introduced. We show that if the number of agents is 2, a complete description of the core can be found efficiently. However, when the number of agents is not restricted, the problem to decide the nonemptyness of the core becomes NP-hard already in the case of two types of goods. We also show that even the problem to decide whether an allocation exists in which each agent strictly improves compared to his endowment, is NP-complete.

##### MSC:
 91A12 Cooperative games 91A06 $$n$$-person games, $$n>2$$ 68Q17 Computational difficulty of problems (lower bounds, completeness, difficulty of approximation, etc.) 91B54 Special types of economic markets (including Cournot, Bertrand)
##### Keywords:
NP-completeness; core; Shapley-Scarf economy; algorithm
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##### References:
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