Module: Mathlib.LinearAlgebra.AffineSpace.Ceva

Goal state before:
pp: case refine_1
k : Type u_1
V : Type u_2
P : Type u_3
ι : Type u_4
inst✝³ : Ring k
inst✝² : AddCommGroup V
inst✝¹ : Module k V
inst✝ : AffineSpace V P
p : ι → P
hp : AffineIndependent k p
s : Set ι
fs : ↑s → Finset ι
hfs : ∀ (i : ↑s), ↑i ∈ fs i
w : ↑s → ι → k
hw : ∀ (i : ↑s), ∑ j ∈ fs i, w i j = 1
p' : P
hp' : ∀ (i : ↑s), p' ∈ line[k, p ↑i, (Finset.affineCombination k (fs i) p) (w i)]
hp'' : ∀ (i : ↑s), ∃ r, (Finset.affineCombination k (fs i) p) ((AffineMap.lineMap (Pi.single (↑i) 1) (w i)) r) = p'
i' : ι
hi' : i' ∈ s
ri' : k
hri' :
  (Finset.affineCombination k (fs ⟨i', hi'⟩) p) ((AffineMap.lineMap (Pi.single (↑⟨i', hi'⟩) 1) (w ⟨i', hi'⟩)) ri') = p'
w' : ι → k := (AffineMap.lineMap (Pi.single i' 1) (w ⟨i', hi'⟩)) ri'
⊢ ∑ j ∈ fs ⟨i', hi'⟩, w' j = 1

pp: case refine_2
k : Type u_1
V : Type u_2
P : Type u_3
ι : Type u_4
inst✝³ : Ring k
inst✝² : AddCommGroup V
inst✝¹ : Module k V
inst✝ : AffineSpace V P
p : ι → P
hp : AffineIndependent k p
s : Set ι
fs : ↑s → Finset ι
hfs : ∀ (i : ↑s), ↑i ∈ fs i
w : ↑s → ι → k
hw : ∀ (i : ↑s), ∑ j ∈ fs i, w i j = 1
p' : P
hp' : ∀ (i : ↑s), p' ∈ line[k, p ↑i, (Finset.affineCombination k (fs i) p) (w i)]
hp'' : ∀ (i : ↑s), ∃ r, (Finset.affineCombination k (fs i) p) ((AffineMap.lineMap (Pi.single (↑i) 1) (w i)) r) = p'
i' : ι
hi' : i' ∈ s
ri' : k
hri' :
  (Finset.affineCombination k (fs ⟨i', hi'⟩) p) ((AffineMap.lineMap (Pi.single (↑⟨i', hi'⟩) 1) (w ⟨i', hi'⟩)) ri') = p'
w' : ι → k := (AffineMap.lineMap (Pi.single i' 1) (w ⟨i', hi'⟩)) ri'
⊢ (Finset.affineCombination k (fs ⟨i', hi'⟩) p) w' = p'

pp: case refine_3
k : Type u_1
V : Type u_2
P : Type u_3
ι : Type u_4
inst✝³ : Ring k
inst✝² : AddCommGroup V
inst✝¹ : Module k V
inst✝ : AffineSpace V P
p : ι → P
hp : AffineIndependent k p
s : Set ι
fs : ↑s → Finset ι
hfs : ∀ (i : ↑s), ↑i ∈ fs i
w : ↑s → ι → k
hw : ∀ (i : ↑s), ∑ j ∈ fs i, w i j = 1
p' : P
hp' : ∀ (i : ↑s), p' ∈ line[k, p ↑i, (Finset.affineCombination k (fs i) p) (w i)]
hp'' : ∀ (i : ↑s), ∃ r, (Finset.affineCombination k (fs i) p) ((AffineMap.lineMap (Pi.single (↑i) 1) (w i)) r) = p'
i' : ι
hi' : i' ∈ s
ri' : k
hri' :
  (Finset.affineCombination k (fs ⟨i', hi'⟩) p) ((AffineMap.lineMap (Pi.single (↑⟨i', hi'⟩) 1) (w ⟨i', hi'⟩)) ri') = p'
w' : ι → k := (AffineMap.lineMap (Pi.single i' 1) (w ⟨i', hi'⟩)) ri'
⊢ ∀ (i : ↑s), ∃ r, ∀ (j : ι), r * (↑(fs i) \ {↑i}).indicator (w i) j = (↑(fs ⟨i', hi'⟩) \ {↑i}).indicator w' j

Tactic:
· simp [w', AffineMap.lineMap_apply_module, Finset.sum_add_distrib, ← Finset.mul_sum, hw, hfs]

Goal state after:
case refine_2
k : Type u_1
V : Type u_2
P : Type u_3
ι : Type u_4
inst✝³ : Ring k
inst✝² : AddCommGroup V
inst✝¹ : Module k V
inst✝ : AffineSpace V P
p : ι → P
hp : AffineIndependent k p
s : Set ι
fs : ↑s → Finset ι
hfs : ∀ (i : ↑s), ↑i ∈ fs i
w : ↑s → ι → k
hw : ∀ (i : ↑s), ∑ j ∈ fs i, w i j = 1
p' : P
hp' : ∀ (i : ↑s), p' ∈ line[k, p ↑i, (Finset.affineCombination k (fs i) p) (w i)]
hp'' : ∀ (i : ↑s), ∃ r, (Finset.affineCombination k (fs i) p) ((AffineMap.lineMap (Pi.single (↑i) 1) (w i)) r) = p'
i' : ι
hi' : i' ∈ s
ri' : k
hri' :
  (Finset.affineCombination k (fs ⟨i', hi'⟩) p) ((AffineMap.lineMap (Pi.single (↑⟨i', hi'⟩) 1) (w ⟨i', hi'⟩)) ri') = p'
w' : ι → k := (AffineMap.lineMap (Pi.single i' 1) (w ⟨i', hi'⟩)) ri'
⊢ (Finset.affineCombination k (fs ⟨i', hi'⟩) p) w' = p'

case refine_3
k : Type u_1
V : Type u_2
P : Type u_3
ι : Type u_4
inst✝³ : Ring k
inst✝² : AddCommGroup V
inst✝¹ : Module k V
inst✝ : AffineSpace V P
p : ι → P
hp : AffineIndependent k p
s : Set ι
fs : ↑s → Finset ι
hfs : ∀ (i : ↑s), ↑i ∈ fs i
w : ↑s → ι → k
hw : ∀ (i : ↑s), ∑ j ∈ fs i, w i j = 1
p' : P
hp' : ∀ (i : ↑s), p' ∈ line[k, p ↑i, (Finset.affineCombination k (fs i) p) (w i)]
hp'' : ∀ (i : ↑s), ∃ r, (Finset.affineCombination k (fs i) p) ((AffineMap.lineMap (Pi.single (↑i) 1) (w i)) r) = p'
i' : ι
hi' : i' ∈ s
ri' : k
hri' :
  (Finset.affineCombination k (fs ⟨i', hi'⟩) p) ((AffineMap.lineMap (Pi.single (↑⟨i', hi'⟩) 1) (w ⟨i', hi'⟩)) ri') = p'
w' : ι → k := (AffineMap.lineMap (Pi.single i' 1) (w ⟨i', hi'⟩)) ri'
⊢ ∀ (i : ↑s), ∃ r, ∀ (j : ι), r * (↑(fs i) \ {↑i}).indicator (w i) j = (↑(fs ⟨i', hi'⟩) \ {↑i}).indicator w' j