Theorem: IncidenceAlgebra.mu_apply_of_eq (LeanCamCombi/Incidence.lean)

State before:
𝕄 : Type u_1
F : Type u_2
𝕜 : Type u_3
𝕝 : Type u_4
𝕞 : Type u_5
α : Type u_6
β : Type u_7
inst✝⁴ : AddCommGroup 𝕜
inst✝³ : One 𝕜
inst✝² : Preorder α
inst✝¹ : LocallyFiniteOrder α
inst✝ : DecidableEq α
a b : α
h : a = b
⊢ (mu 𝕜) a b = 1
Tactic:
rw [mu_apply, if_pos h]
State after:
no goals