Journal of Geometric Analysis

, Volume 20, Issue 3, pp 609–650

Hyperplane Envelopes and the Clairaut Equation

Authors

    • Department of MathematicsIdaho State University
  • H. Turner Laquer
    • Department of MathematicsIdaho State University
Article

DOI: 10.1007/s12220-010-9129-0

Cite this article as:
Fisher, R.J. & Laquer, H.T. J Geom Anal (2010) 20: 609. doi:10.1007/s12220-010-9129-0
  • 70 Views

Abstract

The subject of envelopes has been part of differential geometry from the beginning. This paper brings a modern perspective to the classical problem of envelopes of families of affine hyperplanes. In the process, the classical results are generalized and unified.

A key step in this process is the use of “generalized immersions”. These have been described elsewhere but, briefly, every classical immersion defines a generalized immersion in a canonical way so that generalized immersions can be understood as ordinary immersions “with singularities.” Next, the concept of an envelope is given a modern definition, namely, an envelope is a generalized immersion solving the family that has a universal mapping property relative to all other full rank solutions.

The beauty of this approach becomes apparent in the “Envelope Theorem”. With one mild assumption, namely that the associated family of linear hyperplanes is immersed, it is proven that a family of affine hyperplanes always has an envelope, and that envelope is essentially unique.

Keywords

Hyperplane envelopeGeneralized immersionGauss mapAffine Grassmann dualityClairaut equation

Mathematics Subject Classification (2000)

53C4253A0753A1535D05
Download to read the full article text

Copyright information

© Mathematica Josephina, Inc. 2010