A Ribbon Hopf Algebra Approach to the Irreducible Representations of Centralizer Algebras: The Brauer, Birman-Wenzl, and Type A Iwahori-Hecke Algebras

Arun Ram
Department of Mathematics and Statistics
University of Melbourne
Parkville, VIC 3010 Australia
aram@unimelb.edu.au

Last update: 13 March 2014

Appendix

Weight Polynomials

Qλ(z,q)= (i,i)λ [y+λi-λi] +[hλ(i,i)] [hλ(i,i)] (i,j)λij [y+dλ(i,j)] [hλ(i,j)] Pλ(x)= (i,j)λ x-1+dλ(i,j) hλ(i,j) λ Qλ(z,q) Pλ(x) 1 1 (1) [y+0]+[1] [1] x (12) [y-1]+[2][2] [y+0][1] x(x-1)2 (2) [y+1]+[2][2] [y+0][1] (x+2)(x-1)2 (13) [y-2]+[3][3] [y-1][2] [y+0][1] x(x-2)(x-1)3! (2,1) [y+0]+[3][3] [y+1][2] [y-1][1] (x+2)x(x-2)3 (3) [y+2]+[3][3] [y+1][2] [y+0][1] (x+4)x(x-1)3! (14) [y-3]+[4][4] [y-2][3] [y-1][2] [y+0][1] x(x-3)(x-2)(x-1)4! (2,12) [y-1]+[4][4] [y+1][1] [y-2][2] [y+0][0] (x+1)x(x-3)(x-1)4·2 (22) [y+0]+[3][3] [y+0]+[1][1] [y+0][2] [y+0][2] x(x+2)(x+1)(x-3)3·2·2 (3,1) [y+1]+[4][4] [y+2][2] [y+0][1] [y-1][1] (x+4)(x+1)(x-3)(x-2)4·2 (4) [y+3]+[4][4] [y+2][3] [y+1][2] [y+0][1] (x+6)(x+1)x(x-1)4! [n] = qn-q-n q-q-1 [y+n] = zqn-z-1q-1 q-q-1 hλ(i,j) = λi-i+λj-j+1 dλ(i,j) = { λi+λj-i-j+1 ij -λi- λj+i+j-1 i>j limq1Qλ (q2r,q)= Pλ(2r+1)

Representations of BW(z,q)

We give the representing matrices πλ(gi) for the irreducible representations πλ of BWm(z,q), m=2,3,4 with respect to a given ordered basis v1,v2,,vdλ of 𝒵λ labeled by paths in the Bratelli diagram B. The representations πλ of BWm(z,q) such that |λ|=m are the irreducible representations of the Iwahori-Hecke algebra Hm(q2) of type A.

BW2(z,q)

π(g1)= ( z-1[-y] (1-QQ) ) =(z-1) π (g1)=(q-1[-1]) π (g1)=(q[1]) v1= ( , , ) v1= ( , , ) v1= ( , , )

BW3(z,q)

π(g2)= π(g1)= (q-1[-1]) π(g2)= π(g1)= (q[1]) v1= ( , , , ) v1= ( , , , ) π(g1-)= ( q-1[-1] 0 0 q[1] ) π(g2)= ( q2[2] [1]·[3][2] [1]·[3][2] q-2[-2] ) v1= ( , , , ) v2= ( , , , ) π(g1)= ( q-1[-y](1-QQ) 0 0 0 q-1[-1] 0 0 0 q[1] ) π(g2)= ( z[y] (1-QQ) -q[1] QQQ -q-1[-1] QQQ -q[1] QQQ z-1q2[-y+2] (1-QQ) -z-1[-y] QQQ -q-1[-1] QQQ -z-1[-y] QQQ z-1q-2[-y-2] (1-QQ) ) v1 = ( , , , , ) v2 = ( , , , , ) v3 = ( , , , , )

BW4(z,q)

π(g3)= π(g2)= π(g1)= (q-1[-1]) π(g3)= π(g2)= π(g1)= (q[1]) v1 = ( , , , , ) v1 = ( , , , , ) π(g1)= ( q-1[-1] 0 0 0 q-1[-1] 0 0 0 q[1] ) π(g2)= ( q-1[-1] 0 0 0 q2[2] [1]·[3][2] 0 [1]·[3][2] q-2[-2] ) v1 = ( , , , , ) v2 = ( , , , , ) v3 = ( , , , , ) π(g3)= ( q3[3] [2]·[4][3] 0 [2]·[4][3] q-3[-3] 0 0 0 q-1[-1] ) π(g3)= π(g1)= ( q-1[-1] 0 0 q[1] ) π(g2)= ( q2[2] [1]·[3][2] [1]·[3][2] q-2[-2] ) v1 = ( , , , , ) v2 = ( , , , , ) π(g1)= ( q-1[-1] 0 0 0 q[1] 0 0 0 q[1] ) π(g2)= ( q2[2] [1]·[3][2] 0 [1]·[3] [2] q-2[-2] 0 0 0 q[1] ) v1 = ( , , , , ) v2 = ( , , , , ) v3 = ( , , , , ) π(g3)= ( q[1] 0 0 0 q3[3] [2]·[4][3] 0 [2]·[4][3] q-3[-3] ) π(g3)= π(g1)= ( z-1[-y] (1-QQ) 0 0 0 q-1[-1] 0 0 0 q[1] ) v1 = ( , , , , , ) v2 = ( , , , , , ) v3 = ( , , , , , ) π(g2)= ( z[y] (1-QQ) -q[1] QQQ -q-1[-1] QQQ -q[1] QQQ z-1q2[-y+2] (1-QQ) -z-1[-y] QQQ -q-1[-1] QQQ -z-1[-y] QQQ z-1q-2[-y-2] (1-QQ) ) π(g1)= ( z-1[-y] (1-QQ) 0 0 0 0 0 0 q-1[-1] 0 0 0 0 0 0 q[1] 0 0 0 0 0 0 q-1[-1] 0 0 0 0 0 0 q-1[-1] 0 0 0 0 0 0 q[1] ) π(g2)= ( z[y] (1-QQ) -q[1] QQQ -q-1[-1] QQQ 0 0 0 -q[1] QQQ z-1q2[-y+2] (1-QQ) -z-1[-y] QQQ 0 0 0 -q-1[-1] QQQ -z-1[-y] QQQ z-1q-2[-y-2] (1-QQ) 0 0 0 0 0 0 q-1[-1] 0 0 0 0 0 0 q2[2] [1]·[3][2] 0 0 0 0 [1]·[3][2] q-2[-2] ) π(g3)= ( q-1[-1] 0 0 0 0 0 0 zq-2[y-2] (1-QQ) 0 -q[1] QQQ -q-2[-2] QQQ 0 0 0 z[y] 0 0 [y+1][y-1][y] 0 -q[1] QQQ 0 z-1q4[-y+4] (1-QQ) -z-1q[-y+1] QQQ 0 0 -q-2[-2] QQQ 0 -z-1q[-y+1] QQQ z-1q-2[-y-2] (1-QQ) 0 0 0 [y+1][y-1][y] 0 0 z-1[-y] ) v1 = ( , , , ) v2 = ( , , , ) v3 = ( , , , ) v4 = (, , , , ) v5 = (, , , , ) v6 = (, , , , ) π(g1)= ( z-1[-y] (1-QQ) 0 0 0 0 0 0 q-1[-1] 0 0 0 0 0 0 q[1] 0 0 0 0 0 0 q-1[-1] 0 0 0 0 0 0 q-1[1] 0 0 0 0 0 0 q[1] ) π(g2)= ( z[y] (1-QQ) -q[1] QQQ -q-1[-1] QQQ 0 0 0 -q[1] QQQ z-1q2[-y+2] (1-QQ) -z-1[-y] QQQ 0 0 0 -q-1[-1] QQQ -z-1[-y] QQQ z-1q-2[-y-2] (1-QQ) 0 0 0 0 0 0 q2[2] [1]·[3][2] 0 0 0 0 [1]·[3][2] q-2[-2] 0 0 0 0 0 0 q[1] ) π(g3)= ( q[1] 0 0 0 0 0 0 z[y] 0 [y+1][y-1][y] 0 0 0 0 zq2[y+2] (1-QQ) 0 -q2[2] QQQ -q-1[-1] QQQ 0 [y+1][y-1][y] 0 z-1[-y] 0 0 0 0 -q2[2] QQQ 0 z-1q2[-y+2] (1-QQ) -z-1q-1[-y-1] QQQ 0 0 -q-1[-1] QQQ 0 -z-1q-1[-y-1] QQQ z-1q-4[-y-4] (1-QQ) ) v1 = ( , , , , ) v2 = ( , , , , ) v3 = ( , , , , ) v4 = ( , , , , ) v5 = ( , , , , ) v6 = ( , , , , )

Representations of B(x)

We give the representing matrices πλ(si) and πλ(ei) for the irreducible representations of πλ of Bm(x), m=2,3,4 with respect to a given ordered basis v1,v2,,vdλ of Zλ labeled by paths in the Bratelli diagram B. The representations πλ of Bm(x) such that |λ|=m are the irreducible representations of the group algebra of the symmetric group Sm. In these cases πλ(ei)=0 for all 1im-1.

B2(x)

π(s1)= ( 11-x (1-PP) ) =(1) π (s1)=(-1) π (s1)=(1) π(e1)= (PP) =(x) v1= ( , , ) v1= ( , , ) v1= ( , , )

B3(x)

π(s2)= π(s1)= (-1) π(s2)= π(s1)= (1) v1 = ( , , , ) v1 = ( , , , ) π(s1)= (-1001) π(s2)= ( 12 1·32 1·32 1-2 ) v1 = ( , , , ) v2 = ( , , , ) π(s1)= ( 11-x(1-PP) 0 0 0 -1 0 0 0 1 ) π(e1)= ( PP 0 0 0 0 0 0 0 0 ) π(s2)= ( 1x-1(1-PP) -PPP PPP -PPP 13-x(1-PP) -11-xPPP PPP -11-xPPP 1-(x+1)(1-PP) ) v1 = ( , , , ) v2 = ( , , , ) v3 = ( , , , ) π(e2)= ( PP PPP PPP PPP PP PPP PPP PPP PP ) π(s3)= π(s2)= π(s1)= (-1) π(s3)= π(s2)= π(s1)= (1) v1 = ( , , , , ) v1 = ( , , , , ) π(s1)= ( -100 0-10 000 ) π(s2)= ( -1 0 0 0 12 1·32 0 1·32 1-2 ) v1 = ( , , , , ) v1 = ( , , , , ) v1 = ( , , , , ) π(s3)= ( 1/3 2·43 0 2·43 1-3 0 0 0 -1 ) π(s3)= π(s1)= (-1001) π(s2)= ( 12 1·32 1·32 1-2 ) v1 = ( , , , , ) v2 = ( , , , , ) π(s1)= ( -1 0 0 0 1 0 0 0 1 ) π(s2)= ( 12 1·32 0 1·32 1-2 0 0 0 1 ) v1 = ( , , , , ) v2 = ( , , , ) v3 = ( , , , ) π(s3)= ( 1 0 0 0 1/3 2·43 0 2·43 1-3 ) π(s3)= π(s1)= ( 11-x(1-PP) 0 0 0 -1 0 0 0 1 ) π(e3)= π(e1)= ( PP00 000 000 ) π(s2)= ( 1x-1(1-PP) -PPP PPP -PPP 13-x(1-PP) -11-xPPP PPP -11-xPPP 1-(x+1)(1-PP) ) v1 = ( , , , , ) v2 = ( , , , , ) v3 = ( , , , , ) π(e2)= ( PP PPP PPP PPP PP PPP PPP PPP PP ) π(s1)= ( 11-x(1-PP) 0 0 0 0 0 0 -1 0 0 0 0 0 0 1 0 0 0 0 0 0 -1 0 0 0 0 0 0 -1 0 0 0 0 0 0 1 ) π(s2)= ( 1x-1(1-PP) -PPP PPP 0 0 0 -PPP 13-x(1-PP) -11-xPPP 0 0 0 PPP -11-xPPP 1-(x+1)(1-PP) 0 0 0 0 0 0 -1 0 0 0 0 0 0 12 1·32 0 0 0 0 1·32 1-2 ) π(s3)= ( -1 0 0 0 0 0 0 1x-3(1-PP) 0 -PPP -1-2PPP 0 0 0 1x-1 0 0 x(x-2)x-1 0 -PPP 0 15-x(1-PP) -12-xPPP 0 0 -1-2PPP 0 -12-xPPP 1-(x+1)(1-PP) 0 0 0 x(x-2)x-1 0 0 11-x ) v1 = ( , , , , ) v2 = ( , , , , ) v2 = ( , , , , ) v4 = ( , , , , ) v5 = ( , , , , ) v6 = ( , , , , ) π(e1)= ( PP 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ) π(e2)= ( PP PPP PPP 0 0 0 PPP PP PPP 0 0 0 PPP PPP PP 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ) π(e3)= ( 0 0 0 0 0 0 0 PP 0 PPP PPP 0 0 0 0 0 0 0 0 PPP 0 PP PPP 0 0 PPP 0 PPP PP 0 0 0 0 0 0 0 ) v1 = ( , , , ) v2 = ( , , , ) v3 = ( , , , ) v4 = ( , , , , ) v5 = ( , , , , ) v6 = ( , , , , ) π(s1)= ( 11-x(1-PP) 0 0 0 0 0 0 -1 0 0 0 0 0 0 1 0 0 0 0 0 0 -1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 ) π(s2)= ( 1x-1(1-PP) -PPP PPP 0 0 0 -PPP 13-x(1-PP) -11-xPPP 0 0 0 PPP -11-xPPP 1-(x+1)(1-PP) 0 0 0 0 0 0 1·32 1-2 0 0 0 0 12 1·32 0 0 0 0 0 0 1 ) π(s3)= ( 1 0 0 0 0 0 0 1x-1 0 x(x-2)x-1 0 0 0 0 1x+1(1-PP) 0 -12PPP PPP 0 x(x-2)x-1 0 11-x 0 0 0 0 -12PPP 0 13-x(1-PP) -1-xPPP 0 0 PPP 0 -1-xPPP 1-(x+3)(1-PP) ) v1 = ( , , , , ) v2 = ( , , , , ) v3 = ( , , , , ) v4 = ( , , , , ) v5 = ( , , , , ) v6 = ( , , , , ) π(e1)= ( PP 0 0 0 0 0 000000 000000 000000 000000 000000 ) π(e2)= ( PP PPP PPP 0 0 0 PPP PP PPP 0 0 0 PPP PPP PP 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ) π(e3)= ( 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PP 0 PPP PPP 0 0 0 0 0 0 0 0 PPP 0 PP PPP 0 0 PPP 0 PPP PP ) v1 = ( , , , , ) v2 = ( , , , , ) v3 = ( , , , , ) v4 = ( , , , , ) v5 = ( , , , ) v6 = ( , , , )

Notes and References

This is a typed version of the paper A Ribbon Hopf Algebra Approach to the Irreducible Representations of Centralizer Algebras: The Brauer, Birman-Wenzl, and Type A Iwahori-Hecke Algebras by Robert Leduc* and Arun Ram.

The paper was received June 24, 1994; accepted September 12, 1994.

*Supported in part by National Science Foundation Grant DMS-9300523 to the University of Wisconsin.
Supported in part by National Science Foundation Postdoctoral Fellowship DMS-9107863.

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