Journal of Convex Analysis 19 (2012), No. 3, 815--835
Copyright Heldermann Verlag 2012
Duality of Non-Exposed Faces
Stephan Weis
Max Planck Institute for Mathematics, Inselstraße 22, 04103 Leipzig, Germany, Germany
sweis@mis.mpg.de
Given any polar pair of convex bodies we study its conjugate face maps and we characterize conjugate faces of non-exposed faces in terms of normal cones. The analysis is carried out using the positive hull operator which defines lattice isomorphisms linking three Galois connections. One of them assigns conjugate faces between the convex bodies. The second and third Galois connection is defined between the touching cones and the faces of each convex body separately. While the former is well-known, we introduce the latter in this article for any convex set in any finite dimension. We demonstrate our results about conjugate faces with planar convex bodies and planar self-dual convex bodies, for which we also include constructions.
Keywords: Convex body, polar, conjugate face, non-exposed point, singular face, dual, self-dual.
MSC: 52A10, 52A20
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