simp only [simplification, removeLoops_nonloop_iff, Partition.RepFun.mk_apply]
α : Type u_1
M✝ N : Matroid α
e f✝ g : α
I X P D : Set α
M : Matroid α
f : M.removeLoops.parallelClasses.RepFun := ⋯.some
⊢ M.simplification =
    M ↾
      ⇑{ toFun := ⇑f, apply_eq_self_of_not_mem := ⋯, rel_apply_of_mem := ⋯, apply_eq_of_rel := ⋯ } '' {e | M.Nonloop e}
α : Type u_1
M✝ N : Matroid α
e f✝ g : α
I X P D : Set α
M : Matroid α
f : M.removeLoops.parallelClasses.RepFun := ⋯.some
⊢ M.removeLoops ↾ ⇑⋯.some '' {e | M.Nonloop e} = M ↾ (fun a => f a) '' {e | M.Nonloop e}