All Questions

Suppose we have $x_1^2 + y_1^2 + x_2^2 + y_2^2 + x_3^2 + y_3^2 + x_4^2 + y_4^2 = 1$ and we define $z_j = x_j + iy_j$, where $j = 1,\,2,\,3,\,4$. The problem is finding or approximating the ...

And what are it's applications? A conceptual explanation would be great! Is there an expository note about this somewhere? Some references have already appeared in the answers and comments below. To ...

This post is related to the issues addressed in A q,t-extension of Plancherel Measure thru Yang-Mills Theory ? however the generalization/interpolation which John Mangual asks for looks different ...