Whitney immersion theorem

Whitney immersion theorem

In differential topology, the Whitney immersion theorem states that for m > 1, any smooth m-dimensional manifold can be immersed in Euclidean 2m − 1-space. Equivalently, every smooth m-dimensional manifold can be immersed in the 2m − 1-dimensional sphere (this removes the m > 1 constraint).

The weak version, for 2m, is due to transversality (general position, dimension counting): two m-dimensional manifolds in \mathbf{R}^{2m} intersect generically in a 0-dimensional space.

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Further Results

Massey went on to prove that every n-dimensional manifold is cobordant to a manifold that immerses in S2na(n) where a(n) is the number of 1's that appear in the binary expansion of n. In the same paper, Massey proved that for every n there is manifold (which happens to be a product of real projective spaces) that does not immerse in S2n − 1 − a(n). The conjecture that every n-manifold immerses in S2na(n) became known as the Immersion Conjecture which was eventually solved in the affirmative by Ralph Cohen (Cohen 1985).

See also

References

  • Cohen, Ralph L. (1985), "The Immersion Conjecture for Differentiable Manifolds", The Annals of Mathematics (Annals of Mathematics) 122 (2): 237–328, doi:10.2307/1971304, JSTOR 1971304 

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