Ioffe's criterion and various reformulations of it have become a standard tool in proving theorems guaranteeing metric regularity of a (set-valued) mapping. First, we demonstrate that one should always use directly the so-called general criterion which follows, for example, from Ekeland's variational principle, and that there is no need to make a detour through the slope-based consequences of this general statement. Second, we argue that when proving perturbation stability results, in the spirit of Lyusternik-Graves theorem, there is no need to employ the concept of a lower semi-continuous envelope even in the case of an incomplete target space. The gist is to use the "correct" function to which Ekeland's variational principle is applied; namely, the distance function to the graph of the set-valued mapping under consideration. This approach originates in the notion of graphical regularity introduced by L. Thibault, which is equivalent to the property of metric regularity. Our criteria cover also both metric subregularity and metric semiregularity, which are weaker properties obtained by fixing one of the points in the definition of metric regularity.

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

Radek Cibulka

NTIS - New Technologies for the Information Society, and: Department of Mathematics, Faculty of Applied Sciences, University of West Bohemia, Plzeň, Czech Republic

cibi@kma.zcu.cz

Tomáš Roubal

NTIS - New Technologies for the Information Society, and: Department of Mathematics, Faculty of Applied Sciences, University of West Bohemia, Plzeň, Czech Republic

roubalt@kma.zcu.cz
  1. S. Adly, R. Cibulka, V. N. Huynh: Newton’s method for solving inclusions using set-valued approximations, SIAM J. Optimization 25 (2015) 159–184.https://doi.org/10.1137/130926730Google Scholar
  2. F. J. Aragón Artacho, B. S. Mordukhovich: Enhanced metric regularity and Lipschitzian properties of variational systems, J. Global Optim. 50 (2011) 145–167.https://doi.org/10.1007/s10898-011-9698-xGoogle Scholar
  3. A. Arutyunov, E. Avakov, B. Gel’man, A. Dmitruk, V. Obukhovskii: Locally covering maps in metric spaces and coincidence points, J. Fixed Point Theory Appl. 5 (2009) 105–127.https://doi.org/10.1007/s11784-008-0096-zGoogle Scholar
  4. A. V. Arutyunov, E. R. Avakov, A. F. Izmailov: Directional regularity and metric regularity, SIAM J. Optimization 18 (2007) 810–833.https://doi.org/10.1137/060651616Google Scholar
  5. A. V. Arutyunov, A. F. Izmailov: Directional stability theorem and directional metric regularity, Math. Oper. Res. 31 (2006) 526–543.https://doi.org/10.1287/moor.1060.0203Google Scholar
  6. J.-P. Aubin, H. Frankowska: Set-Valued Analysis, Birkhäuser, Boston (1990).Google Scholar
  7. D. Azé, J. Corvellec: Variational methods in classical open mapping theorems, J. Convex Analysis 13 (2006) 477–488.https://doi.org/10.68381/jca13041Google Scholar
  8. J. M. Borwein, Q. J. Zhu: Techniques of Variational Analysis, CMS Books in Mathematics, Springer, Berlin (2006).https://doi.org/10.1007/978-0-387-31256-9Google Scholar
  9. R. Cibulka, A. L. Dontchev: A nonsmooth Robinson’s inverse function theorem in Banach spaces, Math. Programming Ser. A 156 (2016) 257–270.https://doi.org/10.1007/s10107-015-0877-2Google Scholar
  10. R. Cibulka, A. L. Dontchev, V. M. Veliov: Lyusternik-Graves theorems for the sum of a Lipschitz function and a set-valued mapping, SIAM J. Control Optimization 54 (2016) 3273–3296.https://doi.org/10.1137/16M1063150Google Scholar
  11. R. Cibulka, M. Durea, M. Panţiruc, R. Strugariu: On the stability of the directional regularity, Set-Valued Var. Analysis 28 (2020) 209–237.https://doi.org/10.1007/s11228-019-00507-2Google Scholar
  12. R. Cibulka, M. Fabian: On primal regularity estimates for set-valued mappings, J. Math. Anal. Appl. 438 (2016) 444–464.https://doi.org/10.1016/j.jmaa.2016.02.016Google Scholar
  13. R. Cibulka, M. Fabian, A. Y. Kruger: On semiregularity of mappings, J. Math. Anal. Appl. 473 (2019) 811–836https://doi.org/10.1016/j.jmaa.2018.12.071Google Scholar
  14. R. Cibulka, M. Fabian, T. Roubal: An inverse mapping theorem in Fréchet-Montel spaces, Set-Valued Var. Analysis 28 (2020) 195–208.https://doi.org/10.1007/s11228-020-00536-2Google Scholar
  15. R. Cibulka, T. Roubal: Ioffe-type criteria in extended quasi-metric spaces, J. Convex Analysis 27 (2020) 207–228.https://doi.org/10.68381/jca27012Google Scholar
  16. R. Cibulka, T. Roubal, On ranges of non-linear operators, Set-Valued Var. Analysis 30/2 (2022) 789–810.https://doi.org/10.1007/s11228-021-00619-8Google Scholar
  17. E. De Giorgi, A. Marino, M. Tosques: Problems of evolution in metric spaces and maximal decreasing curve (Italian), Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. 68 (1980) 180–187; English translation in: De Giorgi: Selected papers, Springer, Berlin (2013) 527–533.Google Scholar
  18. A. V. Dmitruk: On a nonlocal metric regularity of nonlinear operators, Control Cybern. 34 (2005) 723–746.Google Scholar
  19. A. V. Dmitruk, A. Y. Kruger: Metric regularity and systems of generalized equations, J. Math. Anal. Appl. 342 (2008) 864–873.https://doi.org/10.1016/j.jmaa.2007.12.057Google Scholar
  20. A. V. Dmitruk, A. A. Milyutin, N. P. Osmolovsky: Lyusternik’s theorem and the theory of extrema, Russian Math. Surveys 35 (1980) 11–51.https://doi.org/10.1070/RM1980v035n06ABEH001973Google Scholar
  21. M. Durea, V. N. Huynh, H. T. Nguyen, R. Strugariu: Metric regularity of composition set-valued mappings: Metric setting and coderivative conditions, J. Math. Anal. Appl. 412 (2014) 41–62.https://doi.org/10.1016/j.jmaa.2013.10.036Google Scholar
  22. M. Durea, R. Strugariu, Chain rules for linear openness in metric spaces and applications, Math. Program. Ser. A 143 (2014) 147–176.https://doi.org/10.1007/s10107-012-0598-8Google Scholar
  23. A. L. Dontchev: The Graves theorem revisited, J. Convex Analysis 3 (1996) 45–53.https://doi.org/10.68381/jca03003Google Scholar
  24. A. L. Dontchev: On existence of solutions of parametrized generalized equations, Set-Valued Var. Analysis 28 (2020) 1–10.https://doi.org/10.1007/s11228-019-00524-1Google Scholar
  25. A. L. Dontchev, H. Frankowska: Lyusternik-Graves theorem and fixed points, Proc. Amer. Math. Soc. 139 (2011) 521–534.https://doi.org/10.1090/S0002-9939-2010-10490-2Google Scholar
  26. A. L. Dontchev, R. T. Rockafellar: Implicit Functions and Solution Mappings, 2nd ed., Springer, Dordrecht (2014).https://doi.org/10.1007/978-1-4939-1037-3Google Scholar
  27. M. Durea, R. Strugariu: Openness stability and implicit multifunction theorems: Applications to variational systems, Nonlinear Analysis 75 (2012) 1246–1259https://doi.org/10.1016/j.na.2011.02.019Google Scholar
  28. M. Fabian, A. D. Ioffe, J. Revalski: Separable reduction of local metric regularity, Proc. Amer. Math. Soc. 146 (2018) 5157–5167.https://doi.org/10.1090/proc/14071Google Scholar
  29. M. Fabian, D. Preiss: A generalization of the interior mapping theorem of Clarke and Pourciau, Comment. Math. Univ. Carolinae 28 (1987) 311–324.Google Scholar
  30. L. M. Graves: Some mapping theorems, Duke Math. J. 17 (1950) 111–114.https://doi.org/10.1215/S0012-7094-50-01713-3Google Scholar
  31. V. N. Huynh, H. T. Nguyen, M. Théra: Metric regularity of the sum of multifunctions and applications, J. Optim. Theory Appl. 160 (2014) 355–390.https://doi.org/10.1007/s10957-013-0385-6Google Scholar
  32. V. N. Huynh, M. Théra: Error bounds in metric spaces and application to the perturbation stability of metric regularity, SIAM J. Optimization 19 (2008) 1–20https://doi.org/10.1137/060675721Google Scholar
  33. V. N. Huynh, M. Théra: Directional metric regularity of multifunctions, Math. Oper. Res. 40 (2015) 969–991https://doi.org/10.1287/moor.2014.0705Google Scholar
  34. A. D. Ioffe: Nonsmooth analysis: Differential calculus of nondifferentiable mappings, Trans. Amer. Math. Soc. 266 (1981) 1–56.https://doi.org/10.1090/S0002-9947-1981-0613784-7Google Scholar
  35. A. D. Ioffe: Metric regularity and subdifferential calculus, Russian Math. Surveys 55 (2000) 501–558.https://doi.org/10.1070/RM2000v055n03ABEH000292Google Scholar
  36. A. D. Ioffe: On regularity concepts in variational analysis, J. Fixed Point Theory Appl. 8 (2010) 339–363.https://doi.org/10.1007/s11784-010-0021-0Google Scholar
  37. A. D. Ioffe: Regularity on a fixed set, SIAM J. Optimization 21 (2011) 1345–1370.https://doi.org/10.1137/110820981Google Scholar
  38. A. D. Ioffe: Variational Analysis of Regular Mappings. Theory and Applications, Springer, Cham (2017).https://doi.org/10.1007/978-3-319-64277-2Google Scholar
  39. B. S. Mordukhovich: Variational Analysis and Generalized Differentiation. I: Basic Theory, Springer, Berlin (2006).https://doi.org/10.1007/3-540-31247-1Google Scholar
  40. H. T. Nguyen, N. H. Dao, V. N. Huynh: Nonlinear metric regularity on fixed sets, Optimization (2022), 34 p.Google Scholar
  41. J.-P. Penot: Calculus without Derivatives, Springer, New York (2013).https://doi.org/10.1007/978-1-4614-4538-8Google Scholar
  42. L. Thibault: Various forms of metric regularity, unpublished note, Université de Montpellier (1999).Google Scholar

R. Cibulka, T. Roubal. “A Quest for Simple and Unified Proofs in Regularity Theory: Perturbation Stability.” Journal of Convex Analysis 30 (2023), No. 3, 771–792. https://doi.org/10.68381/jca30037