Externalities, Nonconvexities, and Fixed Points
Externalities, Nonconvexities, and Fixed Points
Externalities, Nonconvexities, and Fixed Points
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(3) N eE (E ∗ ) ∩ £ U 1 ∪ U 2¤ 6= ∅⇒N eE (E i ) ∩ U i 6= ∅ for some i =1<strong>and</strong>/or 2:WLOG suppose that x ∈ N eE (E ∗ ) ∩ U 1 . Give the definition of the KFC, N eE (·),we have for each y ∈ D(E ∗ ),(y, x) ∈ ¡ E 1 ∩ ¡ X × U 2¢ c ¢ ∪ ¡ E 2 ∩ ¡ X × U 1¢ c ¢ ,<strong>and</strong> because x ∈ U 1 , this implies that for each y ∈ D(E ∗ ),<strong>and</strong> specifically, that for each y ∈ D(E ∗ ),(y, x) ∈ E 1 ∩ ¡ X × U 2¢ c,(y, x) ∈ E 1 ∩ ¡ X × U 1¢ .(*)Thus, given the definition of the D-Restricted KFC, N eE (·), (*) implies thatx ∈ N e E (E1 ) ∩ U 1 ,contradicting the fact that N eE (E 1 ) ∩ U 1 = ∅. Thus we must conclude that N eE (·) hasthe 3M property.References[1] Aliprantis, C. D. <strong>and</strong> Border, K. C. (2006) Infinite Dimensional Analysis: AHitchhiker’s Guide, 3rd Edition, Springer-Verlag, Berlin-Heidelberg.[2] Amir, R. (1996) “Cournot oligopoly <strong>and</strong> the theory of supermodular games,”Games <strong>and</strong> Economic Behavior 15, 132-148.[3] Amir, R. <strong>and</strong> Lazzati, N. (2011) “Network Effects, Market Structure <strong>and</strong> IndustryPerformance,” Journal of Economic Theory 146, 2389-2419.[4] Anguelov, R. <strong>and</strong> Kalenda, O. F. K. (2009) “The Convergence Space of MinimalUSCO Mappings,” Czechoslovak Mathematical Journal 134, 101-128.[5] Beer, G. (1983) “Dense Selections,” Journal of Mathematical Analysis <strong>and</strong> Applications95, 416-427.[6] Beer, G. (1993) Topologies on Closed <strong>and</strong> Closed Convex Sets, KluwerAcademicPublishers, Dordrecht.[7] Berge, C. (1997) Topological Spaces, First Dover Edition, Dover Publishers, Mineola(first published by Dunod, Paris, 1962).[8] Bing, R. H. (1949) “A Convex Metric for a Locally Connected Continuum”Bulletin of the American Mathematical Society 55, 812-819.[9] Blumenthal, M. (1953) Distance Geometry, Oxford University Press, Oxford.57