“…which was introduced in 1987 by Drygas in [4]. The author was looking for characterizations of quasi-inner product spaces, which in turn led to solutions of some problems in statistics and mathematical programming.…”
In the first part of the paper we collect and prove several properties of the Hausdorff metric and the Hukuhara difference. They are applied in the next part where a tool for solving several equations for set-valued functions is described.
“…which was introduced in 1987 by Drygas in [4]. The author was looking for characterizations of quasi-inner product spaces, which in turn led to solutions of some problems in statistics and mathematical programming.…”
In the first part of the paper we collect and prove several properties of the Hausdorff metric and the Hukuhara difference. They are applied in the next part where a tool for solving several equations for set-valued functions is described.
“…The above equation was introduced in [3] in order to obtain a characterization of the quasi-inner-product spaces. Ebanks, Kannappan and Sahoo in [4] have obtained the general solution of the Eq.…”
Abstract.We study the stability of the Drygas functional equation on a restricted domain. The main tool used in the proofs is the fixed point theorem for functional spaces.Mathematics Subject Classification. 39B82, 47H10, 47J20.
“…The equation was introduced in [5], where the author was looking for characterizations of quasi inner product spaces, which in turn led to solutions of some problems in statistics and mathematical programming. The functional equation (1.3) has been studied by Gy.…”
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