Module: Mathlib.LinearAlgebra.AffineSpace.Ceva

Goal state before:
pp: case refine_3.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 : k
hr :
  (Finset.affineCombination k (fs i) p) ((1 - r) • Pi.single (↑i) 1 + r • w i) =
    (Finset.affineCombination k (fs ⟨i', hi'⟩) p) ((1 - ri') • Pi.single i' 1 + ri' • w ⟨i', hi'⟩)
hind :
  (↑(fs i)).indicator ((1 - r) • Pi.single (↑i) 1 + r • w i) =
    (↑(fs ⟨i', hi'⟩)).indicator ((1 - ri') • Pi.single i' 1 + ri' • w ⟨i', hi'⟩)
j : ι
⊢ r * (↑(fs i) \ {↑i}).indicator (w i) j = (↑(fs ⟨i', hi'⟩) \ {↑i}).indicator w' j

Tactic:
by_cases hj : j = i

Goal state after:
case pos
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 : k
hr :
  (Finset.affineCombination k (fs i) p) ((1 - r) • Pi.single (↑i) 1 + r • w i) =
    (Finset.affineCombination k (fs ⟨i', hi'⟩) p) ((1 - ri') • Pi.single i' 1 + ri' • w ⟨i', hi'⟩)
hind :
  (↑(fs i)).indicator ((1 - r) • Pi.single (↑i) 1 + r • w i) =
    (↑(fs ⟨i', hi'⟩)).indicator ((1 - ri') • Pi.single i' 1 + ri' • w ⟨i', hi'⟩)
j : ι
hj : j = ↑i
⊢ r * (↑(fs i) \ {↑i}).indicator (w i) j = (↑(fs ⟨i', hi'⟩) \ {↑i}).indicator w' j

case neg
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 : k
hr :
  (Finset.affineCombination k (fs i) p) ((1 - r) • Pi.single (↑i) 1 + r • w i) =
    (Finset.affineCombination k (fs ⟨i', hi'⟩) p) ((1 - ri') • Pi.single i' 1 + ri' • w ⟨i', hi'⟩)
hind :
  (↑(fs i)).indicator ((1 - r) • Pi.single (↑i) 1 + r • w i) =
    (↑(fs ⟨i', hi'⟩)).indicator ((1 - ri') • Pi.single i' 1 + ri' • w ⟨i', hi'⟩)
j : ι
hj : ¬j = ↑i
⊢ r * (↑(fs i) \ {↑i}).indicator (w i) j = (↑(fs ⟨i', hi'⟩) \ {↑i}).indicator w' j