The aim of this paper is to investigate some fundamental properties of convex sets, cones, and functions in groups and semigroups. In particular, we introduce the concept of quasi core of a convex set, which allows us to provide separation theorems between convex sets in groups where at least one of them has nonempty quasi core. We also analyze optimization problems defined on groups and semigroups and provide saddle point necessary or sufficient optimality conditions by considering suitable Lagrangian functions associated with the given problem.

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

Jun Li

Key Laboratory of Optimization Theory, School of Mathematics and Information, China West Normal University, Nanchong, P. R. China

junli@cwnu.edu.cn
  1. M. Adivar, S. C. Fang: Convex analysis and duality over discrete domains, J. Oper. Res. Soc. China 6 (2018) 189–247.https://doi.org/10.1007/s40305-017-0158-2Google Scholar
  2. J. M. Borwein, O. Giladi: Some remarks on convex analysis in topological groups, J. Convex Analysis 23 (2016) 313–332.https://doi.org/10.68381/jca23012Google Scholar
  3. J. M. Borwein, O. Giladi: Convex analysis in groups and semigroups: a sampler, Math. Program., Ser. B 168 (2018) 11–53.https://doi.org/10.1007/s10107-016-1010-xGoogle Scholar
  4. J. M. Borwein, R. Goebel: Notions of relative interior in Banach spaces, J. Math. Sci. (N.Y.) 115 (2003) 2542–2553.https://doi.org/10.1023/A:1022988116044Google Scholar
  5. J. M. Borwein, A. S. Lewis: Partially finite convex programming. I: Quasi relative interiors and duality theory, Math. Program., Ser. B 57 (1992) 15–48.https://doi.org/10.1007/BF01581072Google Scholar
  6. R. I. Boţ, E. R. Csetnek, G. Wanka: Regularity conditions via quasi-relative interior in convex programming, SIAM J. Optim. 19 (2008) 217–233.https://doi.org/10.1137/07068432XGoogle Scholar
  7. D. V. Cuong, B. S. Mordukhovich, N. M. Nam, A. Cartmell: Algebraic core and convex calculus without topology, Optimization 71 (2022) 309–335.https://doi.org/10.1080/02331934.2020.1800700Google Scholar
  8. F. Flores-Bazán, G. Mastroeni: Strong duality in cone constrained nonconvex optimization, SIAM J. Optim. 23 (2013) 153–169.https://doi.org/10.1137/120861400Google Scholar
  9. S. Fujishige, K. Murota: Notes on L-M -convex functions and the separation theorems, Math. Program., Ser. A 88 (2000) 129–146.https://doi.org/10.1007/PL00011371Google Scholar
  10. R. E. Gomory: Outline of an algorithm for integer solutions to linear programs, Bull. Amer. Math. Soc. 64 (1958) 275–278.https://doi.org/10.1090/S0002-9904-1958-10224-4Google Scholar
  11. R. E. Gomory, W. J. Baumol: Integer programming and pricing, Econometrica 28 (1960) 521–550.https://doi.org/10.2307/1910130Google Scholar
  12. J. B. Hiriart-Urruty, C. Lemaréchal: Convex Analysis and Minimization Algorithms I and II, Springer, Berlin (1993).https://doi.org/10.1007/978-3-662-02796-7Google Scholar
  13. Y. Iwamasa, K. Takazawa: Optimal matroid bases with intersection constraints: valuated matroids, M -convex functions, and their applications, Math. Program., Ser. A 194 (2022) 229–256.https://doi.org/10.1007/s10107-021-01625-2Google Scholar
  14. J. Li, G. Mastroeni: Convex analysis in Z n and applications to integer linear programming, SIAM J. Optim. 30 (2020) 2809–2840.https://doi.org/10.1137/19M1281678Google Scholar
  15. B. L. Miller: On minimizing nonseparable functions defined on the integers with an inventory application, SIAM J. Appl. Math. 21 (1971) 166–185.https://doi.org/10.1137/0121018Google Scholar
  16. K. Murota: Convexity and Steinitz’s exchange property, Adv. Math. 124 (1996) 272–311.https://doi.org/10.1006/aima.1996.0084Google Scholar
  17. K. Murota: Discrete convex analysis, Math. Program., Ser. A 83 (1998) 313–371.https://doi.org/10.1007/BF02680565Google Scholar
  18. K. Murota: Discrete Convex Analysis, SIAM Monographs on Discrete Mathematics and Applications, Society for Industrial and Applied Mathematics, Philadelphia (2003).https://doi.org/10.1137/1.9780898718508Google Scholar
  19. K. Murota, A. Shioura: M -convex function on generalized polymatroid, Math. Oper. Res. 24 (1999) 95–105.https://doi.org/10.1287/moor.24.1.95Google Scholar
  20. G. L. Nemhauser, L. A. Wolsey: Integer and Combinatorial Optimization, Wiley & Sons, New York (1988).https://doi.org/10.1002/9781118627372Google Scholar
  21. M. Volle: Regularizations in abelian complete ordered groups, J. Math. Anal. Appl. 84 (1981) 418–430.https://doi.org/10.1016/0022-247X(81)90178-5Google Scholar
  22. M. Volle: Sur les applications regularisées á valeurs dans un groupe, Math. Oper. Statist. Ser. Optim. 13 (1982) 493–500.https://doi.org/10.1080/02331938208842813Google Scholar

J. Li, G. Mastroeni. “Convex Analysis in Groups and Semigroups and Applications to Separation and Optimization.” Journal of Convex Analysis 32 (2025), No. 4, 989–1022. https://doi.org/10.68381/jca32053