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Minimax Theory and its Applications 03 (2018), No. 2, 227--260 Copyright Heldermann Verlag 2018 The Variational Structure and Time-Periodic Solutions for Mean-Field Games Systems Marco Cirant Dip. di Matematica "Tullio Levi-Civita", Università di Padova, via Trieste 63, 35121 Padova, Italy cirant@math.unipd.it Levon Nurbekyan King Abdullah University of Science and Technology, CEMSE Division, Thuwal 23955-6900, Saudi Arabia levon.nurbekyan@kaust.edu.sa We observe that mean-field game (MFG) systems admit a two-player infinite-dimensional general-sum differential game formulation. We show that particular regimes of this game reduce to previously known variational principles. Furthermore, based on the game-perspective we derive new variational formulations for first-order MFG systems with congestion. Finally, we use these findings to prove the existence of time-periodic solutions for viscous MFG systems with a coupling that is not a non-decreasing function of density. Keywords: Infinite-dimensional differential games, congestion problems, saddle-point formulation. MSC: 35Q91, 35Q93, 35A01. [ Fulltext-pdf (204 KB)] for subscribers only. |