Lean

• The primitive element theorem.
• Galois theory.
• Insolvability of the quintic.
• Frobenius elements.
• Sylow's theorems.
• The Schur-Zassenhaus theorem.
• Burnside's normal p-complement theorem.
• Z-Groups.
• Schreier's lemma.
• Commuting probability of finite groups.
• Irreducibility of x^n-x-1.
• Covering spaces.
• The Pontryagin dual.
• Finite projective planes.