(group-theory-basics)= # Basics This pages contains fundamental results of group theory. ## Theorems :::{prf:theorem} First Isomorphism Theorem Let $G$ and $H$ be two groups, and $f\colon G\to H$ a homomorphism. Let $N$ be a normal subgroup of $G$, and $\varphi\colon G\to G/N$ the natural surjective homomorphism. If $N\subseteq\ker f$, then there exists a unique homomorphism $h\colon G/N\to H$ such that the following diagram commutes: % https://q.uiver.app/#q=WzAsMyxbMCwwLCJHIl0sWzIsMCwiSCJdLFswLDIsIkcvTiJdLFswLDEsImYiXSxbMiwxLCJoIiwyLHsic3R5bGUiOnsiYm9keSI6eyJuYW1lIjoiZGFzaGVkIn19fV0sWzAsMiwiXFx2YXJwaGkiLDJdXQ== :::{tikz} \begin{tikzcd} G && H \\ \\ {G/N} \arrow["f", from=1-1, to=1-3] \arrow["\varphi"', from=1-1, to=3-1] \arrow["h"', dashed, from=3-1, to=1-3] \end{tikzcd} ::: ::: :::{prf:proof} TODO :::