[math] \newcommand{\mathds}{\mathbb}[/math]

Learn a bit about quantum groups, and about easy quantum groups, as to understand the definition of the main [math]8[/math] easy quantum groups, namely

[[math]] \xymatrix@R=20pt@C=20pt{ &K_N^+\ar[rr]&&U_N^+\\ H_N^+\ar[rr]\ar[ur]&&O_N^+\ar[ur]\\ &K_N\ar[rr]\ar[uu]&&U_N\ar[uu]\\ H_N\ar[uu]\ar[ur]\ar[rr]&&O_N\ar[uu]\ar[ur] } [[/math]]

and the Ground Zero theorem in quantum groups, stating that under suitable, strong combinatorial assumptions, these are the only [math]8[/math] quantum groups.