English
Equality of cons with smul: cons g w hmw hgr equals the smul form of head with g.
Русский
Равенство cons с умножением: cons g w hmw hgr равно smul‑форме головы с g.
LaTeX
$$$$cons(g,w,hmw,hgr) = of (\phi := \phi) i g \cdot w.$$$$
Lean4
/-- The equivalence between normal forms and elements of the pushout -/
noncomputable def equiv : PushoutI φ ≃ NormalWord d :=
{ toFun := fun g => g • .empty
invFun := fun w => w.prod
left_inv := fun g => by simp only [prod_smul, prod_empty, mul_one]
right_inv := fun w => prod_smul_empty w }