Theorem: SimpleGraph.degRes_add_sum (Turan4/NbhdRes.lean)

State before:
α : Type u_1
G : SimpleGraph α
inst✝² : Fintype α
inst✝¹ : DecidableEq α
inst✝ : DecidableRel G.Adj
A B C : Finset α
hB : B ⊆ A
⊢ ∑ v in C, degRes G v A = ∑ v in C, degRes G v B + ∑ v in C, degRes G v (A \ B)
Tactic:
rw [← sum_add_distrib]
State after:
α : Type u_1
G : SimpleGraph α
inst✝² : Fintype α
inst✝¹ : DecidableEq α
inst✝ : DecidableRel G.Adj
A B C : Finset α
hB : B ⊆ A
⊢ ∑ v in C, degRes G v A = ∑ x in C, (degRes G x B + degRes G x (A \ B))

State before:
α : Type u_1
G : SimpleGraph α
inst✝² : Fintype α
inst✝¹ : DecidableEq α
inst✝ : DecidableRel G.Adj
A B C : Finset α
hB : B ⊆ A
⊢ ∑ v in C, degRes G v A = ∑ x in C, (degRes G x B + degRes G x (A \ B))
Tactic:
exact sum_congr rfl fun _ _ => G.degRes_add_sub hB
State after:
no goals