Some properties of E -convex functions

Recently, it was shown by Youness [E.A. Youness, On E -convex sets, E -convex functions and E -convex programming, Journal of Optimization Theory and Applications, 102 (1999) 439–450] that many results for convex sets and convex functions actually hold for a wider class of sets and functions, called...

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Bibliographic Details
Published inApplied mathematics letters Vol. 18; no. 9; pp. 1074 - 1080
Main Authors Syau, Yu-Ru, Stanley Lee, E.
Format Journal Article
LanguageEnglish
Published Oxford Elsevier Ltd 01.09.2005
Elsevier
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Summary:Recently, it was shown by Youness [E.A. Youness, On E -convex sets, E -convex functions and E -convex programming, Journal of Optimization Theory and Applications, 102 (1999) 439–450] that many results for convex sets and convex functions actually hold for a wider class of sets and functions, called E -convex sets and E -convex functions. We introduce the concept of E -quasiconvex functions and strictly E -quasiconvex functions, and develop some basic properties of E -convex and E -quasiconvex functions. For a real-valued function f defined on a nonempty E -convex set M , we show under the convexity condition of E ( M ) , that f is E -quasiconvex (resp. strictly E -quasiconvex) if and only if its restriction to E ( M ) is quasiconvex (resp. strictly quasiconvex). Similarly, we show under the convexity condition of E ( M ) , that f is E -convex (resp. strictly E -convex) if and only if its restriction to E ( M ) is convex (resp. strictly convex). In addition, under the convexity condition of E ( M ) , a characterization of an E -quasiconvex function in terms of the lower level sets of its restriction to E ( M ) is also given. Finally, examples in nonlinear programming problem are used to illustrate the applications of our results.
ISSN:0893-9659
1873-5452
DOI:10.1016/j.aml.2004.09.018