rename quot≡0⇒∣ to rem≡0⇒∣
omit unnecessary parentheses
rename _^2 to _²
define distrib-²-* lemma
generalize "s<s*3 : ∀ m → suc m < suc m * 3" to "s<s*ss : ∀ m n → suc m < suc m * suc (suc n)"
clean up