Some characterizations of functions generating K-Schur concave sums and of K-concave set-valued functions
In this note we establish some characterizations of (single valued) unctions, that assume values in a Banach space, generating K-Schur concave sums. These results improve some theorems obtained in  and . Moreover we prove that a set-valued function is K-concave if and only of it is K-t-concave and K-quasi concave (where t is a fixed number in (0,1)). This result improves the theorems obtained in , ,  and extends the theorem of .
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