let lem' := eq_mem_of_equalOnList s₁.support s₁.coords s₂.coords x lem ch₁
R : Type
inst✝² : Ring R
inst✝¹ : DecidableEq R
X : Type
inst✝ : DecidableEq X
s₁ s₂ : FormalSum R X
c₁ : beqOnSupport (FormalSum.support s₁) (FormalSum.coords s₁) (FormalSum.coords s₂) = true
c₂ : beqOnSupport (FormalSum.support s₂) (FormalSum.coords s₁) (FormalSum.coords s₂) = true
ch₁ : equalOnList (FormalSum.support s₁) (FormalSum.coords s₁) (FormalSum.coords s₂) := eql_on_support_of_true c₁
ch₂ : equalOnList (FormalSum.support s₂) (FormalSum.coords s₁) (FormalSum.coords s₂) := eql_on_support_of_true c₂
x : X
h₁ : ¬0 = FormalSum.coords s₁ x
lem : x ∈ FormalSum.support s₁
⊢ FormalSum.coords s₁ x = FormalSum.coords s₂ x
R : Type
inst✝² : Ring R
inst✝¹ : DecidableEq R
X : Type
inst✝ : DecidableEq X
s₁ s₂ : FormalSum R X
c₁ : beqOnSupport (FormalSum.support s₁) (FormalSum.coords s₁) (FormalSum.coords s₂) = true
c₂ : beqOnSupport (FormalSum.support s₂) (FormalSum.coords s₁) (FormalSum.coords s₂) = true
ch₁ : equalOnList (FormalSum.support s₁) (FormalSum.coords s₁) (FormalSum.coords s₂) := eql_on_support_of_true c₁
ch₂ : equalOnList (FormalSum.support s₂) (FormalSum.coords s₁) (FormalSum.coords s₂) := eql_on_support_of_true c₂
x : X
h₁ : ¬0 = FormalSum.coords s₁ x
lem : x ∈ FormalSum.support s₁
lem' : FormalSum.coords s₁ x = FormalSum.coords s₂ x :=
  eq_mem_of_equalOnList (FormalSum.support s₁) (FormalSum.coords s₁) (FormalSum.coords s₂) x lem ch₁
⊢ FormalSum.coords s₁ x = FormalSum.coords s₂ x