Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X42320160601On subdifferential in Hadamard spaces707717807ENM.Soleimani-damaneh{School of Mathematics, Statistics and Computer Science, College of Science, University of
Tehran, Enghelab Avenue, Tehran, Iran.M.MovahediDepartment of Mathematics, Faculty of Sciences, Alzahra University, Tehran, Iran.D.BehmardiDepartment of Mathematics, Faculty of Sciences, Alzahra University, Tehran, Iran.Journal Article20140913In this paper, we deal with the subdifferential concept on Hadamard spaces. Flat Hadamard spaces are characterized, and necessary and suficient conditions are presented to prove that the subdifferential set in Hadamard spaces is nonempty. Proximal subdifferential in Hadamard spaces is addressed and some basic properties are high-lighted. Finally, a density theorem for subdifferential set is established.http://bims.iranjournals.ir/article_807_c964b05ed4b54e1642cbd753e007a371.pdf