diff --git a/library/theories/number_theory/bezout.lean b/library/theories/number_theory/bezout.lean index 349a942e0..152f34c02 100644 --- a/library/theories/number_theory/bezout.lean +++ b/library/theories/number_theory/bezout.lean @@ -73,11 +73,15 @@ end end Bezout +/- +A sample application of Bezout's theorem, namely, an alternative proof that irreducible +implies prime (dvd_or_dvd_of_prime_of_dvd_mul). +-/ + namespace nat open int -theorem dvd_or_dvd_of_dvd_mul_of_prime {p x y : ℕ} (pp : prime p) (H : p ∣ x * y) : - p ∣ x ∨ p ∣ y := +example {p x y : ℕ} (pp : prime p) (H : p ∣ x * y) : p ∣ x ∨ p ∣ y := decidable.by_cases (assume Hpx : p ∣ x, or.inl Hpx) (assume Hnpx : ¬ p ∣ x,