@@ -260,13 +260,14 @@ lemma isSemisimple_ad_of_mem_isCartanSubalgebra {x : L} (hx : x ∈ H) :
260260 replace h_der (y z : L) : S ⁅y, z⁆ = ⁅S y, z⁆ + ⁅y, S z⁆ := by
261261 have hy : y ∈ ⨆ α : H → K, rootSpace H α := by simp [iSup_weightSpace_eq_top]
262262 have hz : z ∈ ⨆ α : H → K, rootSpace H α := by simp [iSup_weightSpace_eq_top]
263- induction hy using LieSubmodule.iSup_induction'
264- · induction hz using LieSubmodule.iSup_induction'
265- · next α y hy β z hz => exact h_der y z α β hy hz
266- · simp
267- · next h h' => simp only [lie_add, map_add, h, h']; abel
268- · simp
269- · next h h' => simp only [add_lie, map_add, h, h']; abel
263+ induction hy using LieSubmodule.iSup_induction' with
264+ | hN α y hy =>
265+ induction hz using LieSubmodule.iSup_induction' with
266+ | hN β z hz => exact h_der y z α β hy hz
267+ | h0 => simp
268+ | hadd _ _ _ _ h h' => simp only [lie_add, map_add, h, h']; abel
269+ | h0 => simp
270+ | hadd _ _ _ _ h h' => simp only [add_lie, map_add, h, h']; abel
270271 /- An equivalent form of the derivation axiom used in `LieDerivation`. -/
271272 replace h_der : ∀ y z : L, S ⁅y, z⁆ = ⁅y, S z⁆ - ⁅z, S y⁆ := by
272273 simp_rw [← lie_skew (S _) _, add_comm, ← sub_eq_add_neg] at h_der; assumption
@@ -419,16 +420,16 @@ lemma traceForm_eq_zero_of_mem_ker_of_mem_span_coroot {α : Weight K H L} {x y :
419420 (hx : x ∈ α.ker) (hy : y ∈ K ∙ coroot α) :
420421 traceForm K H L x y = 0 := by
421422 rw [← coe_corootSpace_eq_span_singleton, LieSubmodule.mem_coeSubmodule, mem_corootSpace'] at hy
422- induction hy using Submodule.span_induction'
423- · next z hz =>
423+ induction hy using Submodule.span_induction' with
424+ | mem z hz =>
424425 obtain ⟨u, hu, v, -, huv⟩ := hz
425426 change killingForm K L (x : L) (z : L) = 0
426427 replace hx : α x = 0 := by simpa using hx
427428 rw [← huv, ← traceForm_apply_lie_apply, ← LieSubalgebra.coe_bracket_of_module,
428429 lie_eq_smul_of_mem_rootSpace hu, hx, zero_smul, map_zero, LinearMap.zero_apply]
429- · simp
430- · next hx hy => simp [hx, hy]
431- · next hz => simp [hz]
430+ | zero => simp
431+ | add _ _ _ _ hx hy => simp [hx, hy]
432+ | smul _ _ _ hz => simp [hz]
432433
433434@[simp] lemma orthogonal_span_coroot_eq_ker (α : Weight K H L) :
434435 (traceForm K H L).orthogonal (K ∙ coroot α) = α.ker := by
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