English
max(max(a,b), c) = max(a, max(b,c)) for all a,b,c in a linear order.
Русский
max(max(a,b), c) = max(a, max(b,c)) для всех a,b,c в линейном порядке.
LaTeX
$$$\max(\max(a,b), c) = \max(a, \max(b,c))$$$
Lean4
theorem max_assoc (a b c : α) : max (max a b) c = max a (max b c) :=
by
apply eq_max
· apply le_trans (le_max_left a b) (le_max_left ..)
· apply max_le
· apply le_trans (le_max_right a b) (le_max_left ..)
· apply le_max_right
· intro d h₁ h₂; apply max_le
· apply max_le h₁; apply le_trans (le_max_left _ _) h₂
· apply le_trans (le_max_right _ _) h₂