4

I have an interesting problem in materials science that I think can be solved by obtaining a mapping, which is one-to-one, continuous and preserves the metric, from spherical 3-manifods (defined as $S^3/\Gamma$, where $\Gamma$ is a finite subgroup of $SO(4)$) to Euclidean space of some dimension $n$ $\left( \mathbb{R}^n \right)$. I believe this mapping is an isometric embedding.

I am primarily interested in obtaining a mapping to any $\mathbb{R}^n$ (not necessarily the smallest $n$ but something reasonable). For example, the group of proper rotations, $SO(3)$, I think, is a spherical 3-manifold ($S^3/(-I_{4\times4}$)), where $I_{4\times4}$ is the $4 \times 4$ identity matrix. This manifold can be isometrically embedded in $\mathbb{R}^9$ through the $3 \times 3$ matrix representation of that rotation. I am wondering if such embeddings are known for other spherical 3-manifolds. Any help is greatly appreciated.

Edit 1: I want to make this a little more specific if it helps. I am interested in the isometric embedding of $S^3/2O$, where $2O$ is the binary ocatahedral point group (https://en.wikipedia.org/wiki/Binary_octahedral_group). Alternatively, this space is equivalent to the quotient space $SO(3)/O$, where $O$ is the octahedral point group $(2,3,4)$.

Moishe Kohan
  • 97,719
  • 1
    If you just want existence, I think you may want to look at the second Nash embedding theorem. It's much, much more powerful than what you're looking for. Another point to consider is that all spherical manifolds are quotients of the isometry group $SO(4)$, so that may be exploitable for this particular problem. – Neal Aug 26 '16 at 02:14
  • @Neal - More than just the existence, I am interested in the mapping. The embedding of SO(3) is an example where I know the mapping from quaternions to a 3×3×3 matrix. I don't know much about the properties of quotient spaces of SO(4)SO(4). Could you provide me with any resources that I could read. Thanks! – Srikanth Aug 26 '16 at 02:32
  • 1
    See for example: https://ldtopology.wordpress.com/2012/07/12/symmetric-decompositions-of-the-4-sphere/ . Relatively few spherical 3-manifolds embed in R^4. The list is due to Jon Hillman, and appears here: http://front.math.ucdavis.edu/0810.2346 – Ryan Budney Aug 26 '16 at 17:26
  • See the discussion at http://mathoverflow.net/questions/31222/c1-isometric-embedding-of-flat-torus-into-mathbbr3 concerning "constructive" versions of Nash isometric embedding. – Moishe Kohan Sep 02 '16 at 16:00
  • 1
    +1. This is a GREAT question. If there's no answers I might put a bounty. I looked at your profile and saw you followed a proposal for a Materials Modeling Stack Exchange. If you don't mind another attempt at a Materials proposal, would you be so kind to commit to this? https://area51.stackexchange.com/proposals/122958/materials-modeling?referrer=ZTUyZWY5OTQ1NDI4ZGVlMmU5MzM0ZThiZjNhOTRkYWFlMTA1NjM0OWEzOTZhYzlmMTBlNWQ4ZmIzYWE3MWFkN-4At28O9gekwyERVbYPhFIPwyHiajfB5BeMyrZKJaYV0 It started slow but lately it's been booming with 5 commitments/day and very soon it will reach 200. – Nike Dattani Mar 26 '20 at 19:51

0 Answers0