I wonder if this could be “the start of something new”.

Let’s start with sub-Riemannian geometry and tag my posts “sR” and “maths”. I may put up other findings as well. Apologies for links that require institutional access, such as academic journals related to my studies.

3 July 2014 20:55:50

Q.A1 Why ?

Q.A2 What reparametrization leads to with a.e. and length as specified?

Q.A3 Finish Chapter 3.

Q.B1 Montgomery‘s proof of abnormal geodesics (compared with the one in the book).

Q.C1 R. Monti’s paper on the regularity problem for sub-Riemannian geodesics.

Log of activity since 4th July 2014. Rough work in my hands.

Useful information, unsorted

- All things
**Lie**: Given , denoting multiplication, and , the**Lie bracket**is defined by . The**Lie algebra**is a vector space over a field with the binary operation .- Question: Given two vector fields , how does one find the Lie bracket ?

**contact**(of a distribution) : given frame fields defined near a point , the vectors and Lie brackets form a basis for the tangent space at .**fiber**of a map : any subset of the form for some .- : Heisenberg group, sub-Riemannian
**a.e.**: almost everywhere**reparametrization**: given a parametrized curve , a parametrized curve is a**reparametrization**of if there exists a diffeomorphism (=bijective and smooth function with smooth inverse) such that .

- Latex Math Symbols: http://web.ift.uib.no/Teori/KURS/WRK/TeX/symALL.html
- LaTeX does not work on Android devices. I hope there’s a way to make it work.

- http://en.wikipedia.org/wiki/Lie_bracket_of_vector_fields
- http://en.wikipedia.org/wiki/Lie_derivative
- http://en.wikipedia.org/wiki/Covariant_derivative
- http://en.wikipedia.org/wiki/Connection_(mathematics)
- http://en.wikipedia.org/wiki/Fiber_bundle
- http://en.wikipedia.org/wiki/Vector_field
- “An Introduction to Heisenberg Groups in Analysis and Geometry” by Stephen Semmes [pdf] http://t.co/xOgl0Xnx49
- …

- SpringerLink
- Andrew Pressley,
*Elementary Differential Geometry* - John M. Lee,
*Introduction to Smooth Manifolds* - John M. Lee,
*Introduction to Topological Manifolds* - Stefani, G., Boscain, U., Gauthier, J.-P., Sarychev, A., Sigalotti, M. (Eds.),
*Geometric Control Theory and Sub-Riemannian Geometry*

- Andrew Pressley,