Wednesday, 16 November 2011

rt.representation theory - Signed and unsigned Hecke algebra canonical basis

You probably know all of this already, but here goes...



Write Cw=Tw+sumx<wpx,wTx where px,winumathbbZ[u]. Now, the other basis can be defined by applying the involutive automorphism b:mathcalHntomathcalHn, given by b(Tw)=Tw and b(u)=u1.




Define Cw:=b(Cw).




Since, b commutes with the bar involution, this basis is bar invariant as well.



Explicitly, Cw=Tw+sumx<w(1)ell(w)+ell(x)barpx,wTx.



So Cw=barP1PCw which seems hard to compute in general.

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