منابع مشابه
Convexity of Nilpotent Balls
We consider the shape of balls for nilpotent Lie groups endowed with a left invariant Riemannian or sub-Riemannian metric. We prove that when the algebra is graded these balls are homeomorphic to the standard Euclidean ball. For two-step nilpotent groups we show that the intersections of the ball with the central cosets are star-shaped, and in special cases convex.
متن کاملLOCAL CONVEXITY PROPERTIES OF j-METRIC BALLS
This paper deals with local convexity properties of the j-metric. We consider convexity and starlikeness of the j-metric balls in convex, starlike and general subdomains of R.
متن کاملTouching Graphs of Unit Balls
The touching graph of balls is a graph that admits a representation by non-intersecting balls in the space (of prescribed dimension), so that its edges correspond to touching pairs of balls. By a classical result of Koebe [?], the disc touching graphs are exactly the planar graphs. This paper deals with a recognition of unit-ball touching graphs. The 2– dimensional case was proved to be NP-hard...
متن کاملBest approximation by closed unit balls
We obtain a sucint and nesessery theoreoms simple for compactness andweakly compactness of the best approximate sets by closed unit balls. Also weconsider relations Kadec-Klee property and shur property with this objects.These theorems are extend of papers mohebi and Narayana.
متن کاملLocal Convexity Properties of Balls in Apollonian and Seittenranta’s Metrics
We consider local convexity properties of balls in the Apollonian and Seittenranta’s metrics. Balls in the Apollonian metric are considered in the twice punctured space and starlike domains. Balls in Seittenranta’s metric are considered in the twice punctured space and in the punctured ball.
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ژورنال
عنوان ژورنال: Journal of Mathematical Analysis and Applications
سال: 2017
ISSN: 0022-247X
DOI: 10.1016/j.jmaa.2016.04.022