nLab covering of alternating group

Idea

The universal group extension of alternating groups $A_n$.

Properties

These are double covers except for the alternating groups of degree $n = 6$ and 7 where the covers are 6-fold.

Examples

• for $A_5$: binary icosahedral group

Related concepts

• symmetric group – Whitehead tower

Reference

• Wikipedia, Covering groups of the alternating and symmetric groups