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Journal of Convex Analysis 25 (2018), No. 2, 389--402 Copyright Heldermann Verlag 2018 On Minimax Theorems for Lower Semicontinuous Functions in Hilbert Spaces Ewa Bednarczuk System Research Institute, Polish Academy of Sciences, Newelska 6, 01-447 Warsaw, Poland and: Faculty of Mathematics and Information Science, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw, Poland Ewa.Bednarczuk@ibspan.waw.pl Monika Syga Faculty of Mathematics and Information Science, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw, Poland M.Syga@mini.pw.edu.pl We prove minimax theorems for lower semicontinuous functions defined on a Hilbert space. The main tools are the theory of Φ-convex functions and sufficient and necessary conditions for the minimax equality for general Φ-convex functions. The conditions we propose are expressed in terms of abstract Φ-subgradients. Keywords: Abstract convexity, minimax theorems, intersection property, abstract Phi-subdifferential, abstract Phi-subgradient. MSC: 32F17, 49J52, 49K27, 49K35, 52A01 [ Fulltext-pdf (112 KB)] for subscribers only. |