English
If s0 ⊆ s1 and t0 ⊆ t1 then seq s0 t0 ⊆ seq s1 t1; i.e., the seq operation is monotone in both arguments.
Русский
Если s0 ⊆ s1 и t0 ⊆ t1, то seq s0 t0 ⊆ seq s1 t1; то есть операция seq монотонна по обеим аргументам.
LaTeX
$$$$ \\text{seq}(s_0,t_0) \\subseteq \\text{seq}(s_1,t_1) $$$$
Lean4
@[gcongr, mono]
theorem seq_mono {s₀ s₁ : Set (α → β)} {t₀ t₁ : Set α} (hs : s₀ ⊆ s₁) (ht : t₀ ⊆ t₁) : seq s₀ t₀ ⊆ seq s₁ t₁ :=
image2_subset hs ht