# Start a new discussion

## Not signed in

Want to take part in these discussions? Sign in if you have an account, or apply for one below

## Discussion Tag Cloud

Vanilla 1.1.10 is a product of Lussumo. More Information: Documentation, Community Support.

• CommentRowNumber1.
• CommentAuthorUrs
• CommentTimeMay 27th 2013

created equivariant de Rham cohomology with a brief note on the Cartan model.

(I seem to remember that we had discussion of this in the general context of Lie algebroids elsewhere already, several years back. But now I cannot find it….)

• CommentRowNumber2.
• CommentAuthorUrs
• CommentTimeFeb 3rd 2015
• (edited Feb 3rd 2015)

I have fixed a bunch of typographical glitches at equivariant de Rham cohomology . Also added paragraphs cross-linking with Weil algebra.

• CommentRowNumber3.
• CommentAuthorUrs
• CommentTimeJun 20th 2019

• Oliver Goertsches, Leopold Zoller, Equivariant de Rham Cohomology: Theory and Applications, São Paulo J. Math. Sci. (2019) (doi:10.1007/s40863-019-00129-4)
• CommentRowNumber4.
• CommentAuthorUrs
• CommentTimeJun 25th 2019

• CommentRowNumber5.
• CommentAuthorUrs
• CommentTimeJun 25th 2019

and harmonized the list of references here with that at Weil algebra

• CommentRowNumber6.
• CommentAuthorUrs
• CommentTimeJun 25th 2019

finally spelled out the details of the Weil model: here

• CommentRowNumber7.
• CommentAuthorUrs
• CommentTimeJun 25th 2019

I thought I’d follow Miettinen’s hep-th/9612209 for a concise and readable account of passing from Weil via Kalkman to Cartan. But if we accept the conjugation in his (14) don’t we get an extra quadratic term in (13)?

With the notation that I am using now in the entry (here), I get

\begin{aligned} d_K & = \exp\big( -t^a \wedge \iota_{v^a} \big) \circ \big( d_{dR} + d_W \big) \circ \exp\big( t^a \wedge \iota_{v^a} \big) \\ & = d_{dR} + d_W + \big[ d_{dR} + d_W, t^a \wedge \iota_{v^a} \big] \\ & = d_{dR} + d_W + \big[ d_W, t^a \big] \wedge \iota_{v^a} - t^a \wedge \big[ d_{dR}, \iota_{v^a} \big] \\ & = d_{dR} + d_W + \big( r^a \underbrace{ - \tfrac{1}{2}f_{b c}^a t^b \wedge t^c } \big) \wedge \iota_{v^a} - t^a \wedge \mathcal{L}_{v^a} \end{aligned}

where the term over the brace is not in (13) of hep-th/9612209 .

Of course this is all elementary. Maybe I need to take a break…

• CommentRowNumber8.
• CommentAuthorUrs
• CommentTimeJun 26th 2019

Oh, I see. Will edit…

• CommentRowNumber9.
• CommentAuthorUrs
• CommentTimeJun 26th 2019

Okay, I have brought in statement and proof of a big lemma (here) explainng how the Cartan model is the result of solving in the Weil model the horizontality condition by applying the corresponding projection operator.

This is just an exegesis of Mathai-Quillen 86 around (5.6), which in turn follows the original

• Henri Cartan, Sec. 6 of La transgression dans un groupe de Lie et dans un espace fibré principal, Colloque de topologie (espaces fibrés). Bruxelles, 1950

If anyone has more publication details on this article of Cartan, in particular maybe a scan, we should add it.

• CommentRowNumber10.
• CommentAuthorUrs
• CommentTimeJun 27th 2019

• CommentRowNumber11.
• CommentAuthorUrs
• CommentTimeJun 27th 2019

added statement of the equivariant de Rham theorem (here)

• CommentRowNumber12.
• CommentAuthorUrs
• CommentTimeJun 27th 2019

Generalization of the equivariant de Rham theorem to non-compact Lie groups is due to

based on the simplicial de Rham complex

• CommentRowNumber13.
• CommentAuthorUrs
• CommentTimeJun 28th 2019
• (edited Jun 28th 2019)

I have added the proof idea of the equivariant de Rham theorem (here), explaining how the Weil model is the image in dgc-algebraic rational homotopy theory of the Borel construction.

To make this proof idea a proof one needs to add some facts about resolutions in $\mathfrak{g}$-rational homotopy theory. The usual sources all shy away from going this last step. What’s a source that goes all the way?

• CommentRowNumber14.
• CommentAuthorUrs
• CommentTimeOct 23rd 2020

• Jaap Kalkman, BRST Model for Equivariant Cohomology and Representatives for the Equivariant Thom Class, Comm. Math. Phys. Volume 153, Number 3 (1993), 447-463. (euclid:1104252784)
• CommentRowNumber15.
• CommentAuthorUrs
• CommentTimeOct 28th 2020

• CommentRowNumber16.
• CommentAuthorUrs
• CommentTimeOct 29th 2020

added brief statement of the Cartan map (here)

• CommentRowNumber17.
• CommentAuthorUrs
• CommentTimeOct 29th 2020

Question: Does any author make explicit the zig-zag of quasi-isomorphisms between the Cartan model of a smooth $G$-action on a manifold $X$ and the PL de Rham complex of the Borel space $X \sslash G$?

• CommentRowNumber18.
• CommentAuthorUrs
• CommentTimeOct 30th 2020

• Please log in or leave your comment as a "guest post". If commenting as a "guest", please include your name in the message as a courtesy. Note: only certain categories allow guest posts.
• To produce a hyperlink to an nLab entry, simply put double square brackets around its name, e.g. [[category]]. To use (La)TeX mathematics in your post, make sure Markdown+Itex is selected below and put your mathematics between dollar signs as usual. Only a subset of the usual TeX math commands are accepted: see here for a list.

• (Help)