We introduce a new notion of subdifferential, which we call Q-subdifferential, for functions defined on subsets of normed spaces. The Q-subdifferential is a subset of the Greenberg-Pierskalla quasi-subdifferential and is therefore useful in quasiconvex analysis.

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

J. E. Martínez-Legaz

Dep. d'Economia i d'Història Econòmica, Universitat Autònoma de Barcelona, 08193 Bellaterra - Barcelona, Spain

P. H. Sach

Dep. d'Economia i d'Història Econòmica, Universitat Autònoma de Barcelona, 08193 Bellaterra - Barcelona, Spain

  1. M. Avriel, W. Diewert, S. Schaible, I. Zang: Generalized Concavity, New York, Plenum Press, 1988.https://doi.org/10.1007/978-1-4684-7600-2Google Scholar
  2. R. Correa, A. Jofré, L. Thibault: Characterization of lower semicontinuous convex functions, Proceedings of the American Mathematical Society 116 (1992) 67-72.https://doi.org/10.1090/S0002-9939-1992-1126193-4Google Scholar
  3. R. Correa, A. Jofré, L. Thibault: Subdifferential monotonicity as characterization of convex functions, Numerical Functional Analysis and Optimization 15 (1994) 531-535.https://doi.org/10.1080/01630569408816579Google Scholar
  4. J. P. Crouzeix: Duality between direct and indirect utility functions: differentiability properties, Journal of Mathematical Economics 12 (1983) 149-165.https://doi.org/10.1016/0304-4068(83)90010-1Google Scholar
  5. R. Ellaia, H. Hassouni: Characterization of nonsmooth functions through their generalized gradients, Optimization 22 (1991) 401-416.https://doi.org/10.1080/02331939108843678Google Scholar
  6. S. Karamardian, S. Schaible: Seven kinds of monotone maps, Journal of Optimization Theory and Applications 66 (1990) 37-46.https://doi.org/10.1007/BF00940531Google Scholar
  7. D. T. Luc, S. Swaminathan: A characterization of convex functions, Nonlinear Analysis, Theory, Methods and Applications 30 (1993) 697-701.https://doi.org/10.1016/0362-546X(93)90027-PGoogle Scholar
  8. D. T. Luc: Characterization of quasiconvex functions, Bulletin of the Australian Mathematical Society 48 (1993) 393-405.https://doi.org/10.1017/S0004972700015859Google Scholar
  9. J. E. Martinez-Legaz: Quasiconvex duality theory by generalized conjugation methods, Optimization 19 (1988) 603-652.https://doi.org/10.1080/02331938808843379Google Scholar
  10. J. E. Martinez-Legaz: Weak lower subdifferentials and applications, Optimization 21 (1990) 321-341.https://doi.org/10.1080/02331939008843551Google Scholar
  11. J. P. Penot, P. H. Quang: Generalized convexity of functions and generalized monotonicity of set-valued maps, Journal of Optimization Theory and Applications 92 (1997) 343-356.https://doi.org/10.1023/A:1022659230603Google Scholar
  12. J. P. Penot, P. H. Sach: Generalized monotonicity of subdifferentials and generalized convexity, Journal of Optimization Theory and Applications 94 (1997) 251-262.https://doi.org/10.1023/A:1022628223741Google Scholar
  13. F. Plastria: Lower subdifferentiable functions and their minimization by cutting planes, Journal of Optimization Theory and Applications 46 (1985) 37-53.https://doi.org/10.1007/BF00938758Google Scholar

J. E. Martínez-Legaz, P. H. Sach. “A New Subdifferential in Quasiconvex Analysis.” Journal of Convex Analysis 6 (1999), No. 1, 1–11. https://doi.org/10.68381/jca06001