English
For n,m ∈ WithBot ℕ, n + m = 2 iff (n = 0 ∧ m = 2) ∨ (n = 1 ∧ m = 1) ∨ (n = 2 ∧ m = 0).
Русский
Для n,m ∈ WithBot ℕ, n + m = 2 тогда и только тогда, когда (n = 0 ∧ m = 2) или (n = 1 ∧ m = 1) или (n = 2 ∧ m = 0).
LaTeX
$$$$ n + m = 2 \\\\iff (n = 0 \\\\land m = 2) \\\\lor (n = 1 \\\\land m = 1) \\\\lor (n = 2 \\\\land m = 0) $$$$
Lean4
theorem add_eq_two_iff {n m : WithBot ℕ} : n + m = 2 ↔ n = 0 ∧ m = 2 ∨ n = 1 ∧ m = 1 ∨ n = 2 ∧ m = 0 :=
by
cases n
· simp [WithBot.bot_add]
cases m
· simp [WithBot.add_bot]
simp [← WithBot.coe_add, Nat.add_eq_two_iff]