Friday, 15 December 2006

Haar measure on a quotient, References for.

I remember reading Weil's "Basic Number Theory" and giving up after a while. Now I find myself thinking of it(thanks to some comments by Ben Linowitz).



Right from the very beginning, Weil uses the fact that when you have a locally compact topolgocal group G and a locally compact subgroup H, in addition to the Haar measures on G and H, there exists a "Haar measure" on the coset space G/H, with some properties.



For instance, the upper half plane mathbbH is the quotient SL2(mathbbR)/SO2(mathbbR) and the usual measure there which gives rise to the usual hyperbolic metric, is arising in this way.



I originally assumed this theorem and went ahead(but not much) with that book.



I want to have a reference for the above theorem. A reference which is not written by Weil. I find him very hard to penetrate. This should exclude Bourbaki's "Integration", as I supppose it would be heavily influenced by him, and thus is a horrible book(note to Harry: this is personal opinion; spare me the brickbats).



I had originally seen the construction of Haar measure on H. Royden's "Real Analysis", in which he is not considering any quotients.

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