Weil algebra of a Lie algebra
Let be a connected Lie group with Lie algebra
. The Weil algebra
of
was first introduced in a series of seminars by H. Cartan [a1], in part based on some unpublished work of A. Weil. As a differential graded algebra, it is given by the tensor product
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where and
denote the exterior and symmetric algebras, respectively (cf. also Exterior algebra; Symmetric algebra).
The Weil algebra and its generalizations have been studied extensively by F.W. Kamber and Ph. Tondeur [a3] [a4]. Let be a maximal compact subgroup, with
denoting the Lie algebra of
. The relative Weil algebra for
is defined by
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With regards to the universal classifying bundle (cf. also Bundle; Classifying space; Universal space), there are canonical isomorphisms in cohomology
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where denotes the
-invariant polynomials. For a given integer
, one has the ideal
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generated by , for
. This leads to the truncated Weil algebra
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The cohomology plays a prominent role in the study of secondary characteristic classes (cf. also Characteristic class) of foliations and foliated bundles [a3] (see also [a2]).
References
[a1] | H. Cartan, "Cohomologie réelle d'un espace fibré principal differentiable" , Sem. H. Cartan 1949/50, Exp. 19–20 (1950) |
[a2] | J.L. Dupont, F.W. Kamber, "On a generalization of Cheeger–Chern–Simons classes" Illinois J. Math. , 34 (1990) |
[a3] | F.W. Kamber, Ph. Tondeur, "Foliated bundles and characteristic classes" , Lecture Notes in Mathematics , 493 , Springer (1975) |
[a4] | F.W. Kamber, Ph. Tondeur, "Semi-simplicial Weil algebras and characteristic classes" Tôhoku Math. J. , 30 (1978) pp. 373–422 |
Weil algebra of a Lie algebra. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Weil_algebra_of_a_Lie_algebra&oldid=24593