Let YY be a real vector metric space and KYK\subset Y be a closed convex cone with K(K)={0}K\cap (-K)=\{0\}. We study properties of set-valued maps F ⁣:R2Y{}F\colon\mathbb{R}\to 2^Y\setminus\{\emptyset\} which are additive modulo KK, i.e. F(x+y)+K=F(x)+F(y)+KF(x+y)+K=F(x)+F(y)+K for x,yRx,y\in \mathbb{R}, and satisfy condition F(xy)+K=xF(y)+yF(x)+KF(xy)+K=xF(y)+yF(x)+K for x,y[0,)x,y\in [0,\infty) (or x,yRx,y\in \mathbb{R}). Such maps are called set-valued derivations modulo KK and generalize the well-known single-valued derivations of R\mathbb{R}.

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Eliza Jablonska

Faculty of Applied Mathematics, AGH University of Krakow, Kraków, Poland

elizajab@agh.edu.pl

E. Jablonska. “On Set-Valued Derivations Modulo K.” Journal of Convex Analysis 32 (2025), No. 4, 1135–1144.