English
Composition compatibly respects leftHomology maps: leftHomologyMap' (φ1 ≫ φ2) h1 h3 equals leftHomologyMap φ1 h1 h2 composed with leftHomologyMap' φ2 h2 h3.
Русский
Составление совместимо сохраняет отображения leftHomologyMap': leftHomologyMap' (φ1 ≫ φ2) h1 h3 равно leftHomologyMap' φ1 h1 h2 затем leftHomologyMap' φ2 h2 h3.
LaTeX
$$leftHomologyMap'(φ1 ≫ φ2) h1 h3 = leftHomologyMap'(φ1) h1 h2 ≫ leftHomologyMap'(φ2) h2 h3$$
Lean4
@[reassoc]
theorem leftHomologyMap'_comp (φ₁ : S₁ ⟶ S₂) (φ₂ : S₂ ⟶ S₃) (h₁ : S₁.LeftHomologyData) (h₂ : S₂.LeftHomologyData)
(h₃ : S₃.LeftHomologyData) :
leftHomologyMap' (φ₁ ≫ φ₂) h₁ h₃ = leftHomologyMap' φ₁ h₁ h₂ ≫ leftHomologyMap' φ₂ h₂ h₃ :=
by
let γ₁ := leftHomologyMapData φ₁ h₁ h₂
let γ₂ := leftHomologyMapData φ₂ h₂ h₃
rw [γ₁.leftHomologyMap'_eq, γ₂.leftHomologyMap'_eq, (γ₁.comp γ₂).leftHomologyMap'_eq, LeftHomologyMapData.comp_φH]