C2 Code

In order to verify some quantum number identities in the $C_2$ clasps paper, one may want to use computer algebra. I learned this technique from Haihan Wu.

We give an example. The identity

$[a+2][2b+2][a+2b+4] = [5][a][2b+2][a+2b+2] −[2][a−1][2b+4][a+2b+2]−[2][a][2b][a+2b+1]$

can be rewritten by replacing $[n]$ with $(q^n- q^{-n})/(q- q^{-1})$. Then if we set $A= q^a$ and $B= q^b$ we obtain an identity in the variables $A, B, q$.

To verify the latter, try typing the following code into https://sagecell.sagemath.org

var('A,B,q')

f(m,n,k)=(A^m*B^n*q^k-1/(A^m*B^n*q^k))/(q-1/q)

ZZ= f(1, 0, 2)*f(0, 2, 2)*f(1, 2, 4)- f(0, 0, 5)*f(1, 0, 0)*f(0, 2, 2)*f(1, 2, 2) + f(0, 0, 2)*f(1, 0, -1)*f(0, 2, 4)*f(1, 2, 2) + f(0, 0, 2)*f(1, 0, 0)*f(0, 2, 0)*f(1, 2, 1)

ZZ.simplify_full()