Subject: categories: universal property of tangent bundle

From: Nikita Danilov <[email-masked]>
Date: Mon, 19 Jul 1999 11:09:43 -0400 (EDT)

Dear category people,

Given an object M in the ``normal'' category of finitely dimensional
smooth manifolds Man (not in SDG sense), what it the universal property
of the tangent bundle TM?

So far, I found only the following:

For every manifold M there is a functor F:I -> Man0, where Man0 is
category of open areas in R^n and smooth mapping, such that M=Colim F,
F corresponding to the atlas on M and M is represented as a result of
gluing instances of R^n in the atlas. This functor can be trivially
modified (by multiplying its values on objects on R^n and modifying
morphisms appropriately) to get functor TF:I -> Man0, such that
TM=Colim TF.

But this doesn't seem satisfactory because:

1. Construction of TF follows one particular construction of TM as a
set of triples (x,(U,f),h) where x \in U, (U,f) is in atlas and h \in
R^n with appropriate points identified.

2. I hope there should be universal construction with \pi: TM -> M as
universal arrow.

3. As tangent bundle is so ubiquitous there should be nice universal
property for it.

With regards,
N. Danilov.