Abstract
In this paper, the subadditivity and superadditivity of convex functions and concave functions on positive operators are proved by applying the function orders preserving or reversing operator inequalities. Moreover, a version of Jensen’s operator inequality without operator convexity is applied to obtain some results on subadditivity or superadditivity of a class of non-negative functions which are not necessarily convex or concave.
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Anjidani, E. On Subadditivity and Superadditivity of Functions on Positive Operators. Mediterr. J. Math. 18, 205 (2021). https://doi.org/10.1007/s00009-021-01855-w
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DOI: https://doi.org/10.1007/s00009-021-01855-w
Keywords
- Operator inequalities
- subadditivity
- superadditivity
- function order of positive operator
- Jensen’s operator inequality