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Some general constructions of tight mappings

Published online by Cambridge University Press:  14 November 2011

Leslie Coghlan
Affiliation:
Department of Mathematics, University of Alabama at Birmingham, University Station, Birmingham, AL 35294, U.S.A.

Synopsis

We present several general methods of constructing tight hypersurfaces f: MnEn+1, n ≧ 2. We prove a smoothing lemma, which allows us to approximate tight continuous hypersurfaces by C tight ones. We show that given a tight immersion or C-stable map f: M2E3 of a compact surface M2 other than S2, there is a tight C∞-stable map g: M2 # RP2:→ E3. We prove that given C tight immersions f: MnEn+1 and g: NnEn+1 of compact n-manifolds Mn and Nn into En+1, there is a tight C immersion of Mn # Nn into En+1. Two other methods involve hypersurfaces of rotation and sets in En+1 at a fixed distance from a tightly embedded n-manifold with boundary in En. One consequence of these methods is that the outer part of C tight hypersurfacesf: MnEn+1, n ≧ 3, is far more complicated than in the case of tight surfaces in En. For example, given any Cn-manifold M with boundary tightly embedded in En, there is a tight immersion f:NnEn+1 of a closed n-manifold having M as a topset. Kuiper's theorem describing tight immersions of surfaces into E3 does not generalise to the case of hypersurfaces f: MnEn+1, n ≧ 3, without substantial restrictions on Mn and/or f.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1989

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