## Libor Vesel\'y

*The distance between subdifferentials in the terms of functions *

Comment.Math.Univ.Carolinae 34,3 (1993) 419-424. **Abstract:**For convex continuous functions $f,g$ defined respectively in neighborhoods of points $x,y$ in a normed linear space, a formula for the distance between $\partial f(x)$ and $\partial g(y)$ in terms of $f,g$ (i.e. without using the dual) is proved. Some corollaries, like a new characterization of the subdifferential of a continuous convex function at a point, are given. This, together with a theorem from [4], implies a sufficient condition for a family of continuous convex functions on a barrelled normed linear space to be locally uniformly Lipschitz.

**Keywords:** convex analysis, subdifferentials of convex functions, barrelled normed linear spaces

**AMS Subject Classification:** Primary 26B25, 52A41; Secondary 46A08

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