English
If B1 ⊆ B2, then FreimanIso n A B1 f implies FreimanIso n A B2 f.
Русский
Если B1 ⊆ B2, то FreimanIso n A B1 f имплицирует FreimanIso n A B2 f.
LaTeX
$$subset (hB) (hf) (hf' ) : IsMulFreimanIso n A B1 f$$
Lean4
@[to_additive]
theorem subset (hA : A₁ ⊆ A₂) (hf : IsMulFreimanIso n A₂ B₂ f) (hf' : BijOn f A₁ B₁) : IsMulFreimanIso n A₁ B₁ f
where
bijOn := hf'
map_prod_eq_map_prod s t hsA htA hs
ht := by refine hf.map_prod_eq_map_prod (fun a ha ↦ hA (hsA ha)) (fun a ha ↦ hA (htA ha)) hs ht