simp at h1
Node : Type
inst : DecidableEq Node
xs ys zs : List Node
S : Set Node
x : Node
h1 : ∀ x_1 ∈ S, x_1 ∈ {x} ∪ ↑zs.toFinset ∪ ↑ys.toFinset
⊢ ↑xs.toFinset ∪ S ⊆ ↑(xs ++ zs).toFinset ∪ ↑(x :: ys).toFinset
Node : Type
inst : DecidableEq Node
xs ys zs : List Node
S : Set Node
x : Node
h1 : ∀ x_1 ∈ S, (x_1 = x ∨ x_1 ∈ zs) ∨ x_1 ∈ ys
⊢ ↑xs.toFinset ∪ S ⊆ ↑(xs ++ zs).toFinset ∪ ↑(x :: ys).toFinset