Muller-Schuppの定理のpdf,ようやく自由群,群の表示,自由積,融合積,ピンポン補題とSL(2,Z)のSanov部分群まで書いた.あとは半直積とHNN拡大を書くぞ
A Mastodon instance named Mathtodon, where you can post toots with beautiful mathematical formulae in TeX/LaTeX style.