have : n < k := lt_trans ‹n < m› ‹m < k›
ℕ : Type
inst✝³ : Core ℕ
inst✝² : Induction ℕ
inst✝¹ : Addition ℕ
inst✝ : Sign ℕ
order_inst : Order ℕ
n m k : ℕ
x✝¹ : n < m
x✝ : m ≤ k
this : m < k ∨ m ≃ k
h✝ : m < k
⊢ n < k
ℕ : Type
inst✝³ : Core ℕ
inst✝² : Induction ℕ
inst✝¹ : Addition ℕ
inst✝ : Sign ℕ
order_inst : Order ℕ
n m k : ℕ
x✝¹ : n < m
x✝ : m ≤ k
this✝ : m < k ∨ m ≃ k
h✝ : m < k
this : n < k
⊢ n < k