Let $\Gamma$ be a finite subgroup of $SO(4)$ acting freely on $S^3$. It is known that all such $\Gamma$ can be classified.
Is there any characterization of $\Gamma$ such that $\Gamma$ is conjugate in $O(4)$ to a subgroup of $U(2)$?
Let $\Gamma$ be a finite subgroup of $SO(4)$ acting freely on $S^3$. It is known that all such $\Gamma$ can be classified.
Is there any characterization of $\Gamma$ such that $\Gamma$ is conjugate in $O(4)$ to a subgroup of $U(2)$?