On the Arrow property for symmetric classes of choice functions
نویسنده
چکیده
We prove a re ned version of Shelah's theorem of the Arrow property. Let Cr(A) be the set of all choice functions de ned on the r-element subsets of a nite set A. Then any non-empty proper symmetric subset D of the set Cr(A) has the Arrow property whenever |A| ≥ 5 and r ≥ 3. We also describe all symmetric sets D ⊂ Cr(A) that have the Arrow property if either r = 2, or r = 3 and |A| = 4.
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تاریخ انتشار 2013