/sci/ - Science & Math

>>14633479
>>14633503
Formally, either [math]0 \to \mathbb{Z} \to \pi_3 (SO(4)) \to \mathbb{Z} \ to 0[/math] is exact, and then it splits, or [math]0 \to \mathbb{Z} \to \pi_3 (SO(4)) \to \mathbb{2Z} \ to 0[/math] is exact, and then it splits, by projectiveness.