∀ (K : Type u_2) {L : Type u_3} [inst : Field K] [inst_1 : Field L] [inst_2 : Algebra K L]
  [inst_3 : IsPurelyInseparable K L] (a : L),
  (minpoly K a).natDegree = ringExpChar K ^ IsPurelyInseparable.elemExponent K a