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.

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J. E. Martinez-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

J. E. Martinez-Legaz, P. H. Sach. “A New Subdifferential in Quasiconvex Analysis.” Journal of Convex Analysis 6 (1999), No. 1, 1–12.