The Alexander polynomial as a universal invariant
The Alexander polynomial as a universal invariant
Let $\mathsf{B}\_1$ be the polynomial ring ${\mathbb C}\[a^{\pm 1},b]$ with the structure of a complex Hopf algebra induced from its interpretation as the algebra of regular functions on the affine linear algebraic group of complex invertible upper triangular $2\times2$ matrices of the form $\left( \begin{smallmatrix} a\&b\0&1 \end{smallmatrix}\right)$. We prove that …