Palatini Formalism generalizes GR to include degenerate metric?

[kakarukeys]

Some papers say that Palatini Formalism still works if the frame variables e^i_a
is not an isomorphism (from tangent bundle to frame bundle), this generalizes GR to include the cases of degenerate metric.

But one could not derive the Einstein's Equation if e^i_a is not an isomorphism!
Somebody please explain to me how it works?

 

[member 11137]

Can you please tell me (us) first what are these "some papers"? Then after having been reading them, I shall try to understand and to answer. Thanks

 

[kakarukeys]

Okay.
For example,
http://arxiv.org/abs/gr-qc/9504036
page 26

and in Lectures on Non-perturbative Canonical Gravity, Abhay Ashtekar
he mentioned a generalization to degenerate metric case.

 

[robphy]

This may be helpful:
http://math.ucr.edu/home/baez/week176.html
http://arxiv.org/abs/gr-qc/9702051
(I haven't read them in detail.)

 

[kakarukeys]

I read them and begin to understand.
But has anyone observed or proposed to observe spacetime of degenerate metric before?