The aim of this article is to establish new two-functions minimax inequalities extending classical results such as Simons' minimax theorem. Our results will be proved in a non-compact setting. We also prove, under general conditions, that the one-function minimax equality is in fact equivalent to the well known Simons inequality. Some applications will be given.

Contact details are reproduced from the original publication and may be historical.

  1. C. D. Aliprantis, K. C. Border: Infinite Dimensional Analysis. A Hitchhiker’s Guide, 3rd ed., Springer, New York (2006).Google Scholar
  2. M. Bachir: A non-convex analogue to Fenchel duality, J. Funct. Anal. 181/2 (2001) 300–312.https://doi.org/10.1006/jfan.2000.3701Google Scholar
  3. M. Bachir: Convex extension of lower semicontinuous functions defined on normal Hausdorff space, J. Convex Analysis 27/3 (2020) 1033–1049.https://doi.org/10.68381/jca27054Google Scholar
  4. M. Bachir: Porosity in the space of Holder-functions, J. Math. Anal. Appl. 509/1 (2022), art.no. 125946.https://doi.org/10.1016/j.jmaa.2021.125946Google Scholar
  5. B. Cascales, J. Orihuela, M. Ruiz Galán: Compactness, optimality, and risk, in: Computational and Analytical Mathematics, D. H. Bailey et al. (eds.), Simon Fraser University, Canada, May 2011, Springer Proceedings in Mathematics and Statistics 50, Springer, New York (2013) 161–218.https://doi.org/10.1007/978-1-4614-7621-4_10Google Scholar
  6. B. D. Craven: Mathematical Programming and Control Theory, Chapman & Hall, London (1978).https://doi.org/10.1007/978-94-009-5796-1Google Scholar
  7. B. D. Craven, B. Mond: Transposition theorems for cone-convex functions, SIAM J. Appl. Math. 24 (1973) 603–612.https://doi.org/10.1137/0124062Google Scholar
  8. R. Deville, C. Finet: An extension of Simons’ inequality and applications, Rev. Mat. Univ. Complut. 14/1 (2001) 95–104.https://doi.org/10.5209/rev_REMA.2001.v14.n1.17044Google Scholar
  9. K. Fan: Minimax theorems, Proc. Nat. Acad. Sci. United States America 39 (1953) 42–47.https://doi.org/10.1073/pnas.39.1.42Google Scholar
  10. K. Fan, I. Glicksberg, A. J. Hoffman: Systems of inequalities involving convex functions, Proc. Amer. Math. Soc. 8 (1957) 617–622.https://doi.org/10.1090/S0002-9939-1957-0087574-2Google Scholar
  11. A. Grothendieck: Critères de compacité dans les espaces fonctionnels généraux, Amer. J. Math. 74 (1952) 168–186.https://doi.org/10.2307/2372076Google Scholar
  12. V. Jeyakumar: Convex-like alternative theorems and mathematical programming, Optimization 16 (1985) 643–652.https://doi.org/10.1080/02331938508843061Google Scholar
  13. V. Jeyakumar, W. Oettli, M. Natividad: A solvability theorem for a class of quasiconvex mappings with applications to optimization, J. Math. Anal. Appl. 179/2 (1993) 537–546.https://doi.org/10.1006/jmaa.1993.1368Google Scholar
  14. K. Kivisoo, E. Oja: Extension of Simons’ inequality, Proc. Amer. Math. Soc. 133/12 (2005) 3485–3496.https://doi.org/10.1090/S0002-9939-05-08267-5Google Scholar
  15. D. Luenberger: Optimization by Vector Space Methods, Wiley, New York (1969).Google Scholar
  16. S. Paeck: Convexlike and concavelike conditions in alternative, minimax, and minimization theorems, J. Optim. Theory Appl. 74/2 (1992) 317–332.https://doi.org/10.1007/BF00940897Google Scholar
  17. V. Ptak: Concerning spaces of continuous functions, Czechoslovak Math. J. 5/80 (1955) 412–431.https://doi.org/10.21136/CMJ.1955.100156Google Scholar
  18. E. Reznichenko: Extension of functions defined on products of pseudocompact spaces and continuity of the inverse in pseudocompact groups, Topol. Appl. 59/3 (1994) 233–244.https://doi.org/10.1016/0166-8641(94)90021-3Google Scholar
  19. T. W. Rishel: Products of countably compact spaces, Proc. Amer. Math. Soc. 58 (1976) 329–330.https://doi.org/10.2307/2041410Google Scholar
  20. M. Ruiz Galán: An intrinsic notion of convexity for minimax, J. Convex Analysis 21/4 (2014) 1105–1139.https://doi.org/10.68381/jca21059Google Scholar
  21. M. Ruiz Galán: The Gordan theorem and its implications for minimax theory, J. Nonlinear Convex Analysis 17/12 (2016) 2385–2405.Google Scholar
  22. M. Ruiz Galán: A theorem of the alternative with an arbitrary number of inequalities and quadratic programming, J. Global Optimization 69/2 (2017) 427–442.https://doi.org/10.1007/s10898-017-0525-xGoogle Scholar
  23. S. Simons: A convergence theorem with boundary, Pacific J. Math. 40/3 (1972) 703–708.https://doi.org/10.2140/pjm.1972.40.703Google Scholar
  24. S. Simons: Minimax and variational inequalities, are they of fixed point or Hahn–Banach type?, in: Game Theory and Mathematical Economics, Proc. Semin. Bonn/Hagen 1980, North Holland, Amsterdam (1981) 379–388.Google Scholar
  25. S. Simons: Minimax theorems and their proofs, in: Minimax and Applications, D.-Z. Du et al. (eds.), Nonconvex Optimization and its Applications 5, Kluwer, Dordrecht (1995) 1–23.https://doi.org/10.1007/978-1-4613-3557-3_1Google Scholar
  26. A. Stefanescu: Alternative and minimax theorems beyond vector spaces, J. Math. Analysis Appl. 264/2 (2001) 450–464.https://doi.org/10.1006/jmaa.2001.7678Google Scholar
  27. A. Stefanescu: A theorem of the alternative and a two-function minimax theorem, J. Appl. Math. 2 (2004) 169–177.https://doi.org/10.1155/S1110757X04304018Google Scholar
  28. R. M. Stephenson, Jr.: Pseudocompact spaces, Trans. Amer. Math. Soc. 134/3 (1968) 437–448.https://doi.org/10.1090/S0002-9947-1968-0232349-6Google Scholar
  29. S. Tomasek: On a certain class of bigwedge-structures. I, II, Czech. Math. J. 20/95 (1970) 1–18, 19–33.https://doi.org/10.21136/CMJ.1970.100941Google Scholar
  30. N. Weaver: Lipschitz Algebras, 2nd ed., World Scientific, Singapore (2018).https://doi.org/10.1142/9911Google Scholar
  31. R. F. Wheeler: Weak and pointwise compactness in the space of bounded continuous functions, Trans. Amer. Math. Soc. 266/2 (1981) 515–530.https://doi.org/10.1090/S0002-9947-1981-0617548-XGoogle Scholar

M. Bachir. “Some New Minimax Theorems for Generalized Convexity.” Journal of Convex Analysis 33 (2026), No. 1&2, 111–130. https://doi.org/10.68381/jca33007