(************************************************************************)
(*         *      The Rocq Prover / The Rocq Development Team           *)
(*  v      *         Copyright INRIA, CNRS and contributors             *)
(* <O___,, * (see version control and CREDITS file for authors & dates) *)
(*   \VV/  **************************************************************)
(*    //   *    This file is distributed under the terms of the         *)
(*         *     GNU Lesser General Public License Version 2.1          *)
(*         *     (see LICENSE file for the text of the license)         *)
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Module Type NLcmPropPrivate
(A : NAxiomsSig') (B : NSubProp A) (C : NDivPropPrivate A B) (D : NGcdProp A B).
Declare Module Private_NLcmProp : NLcmProp A B (C.Private_NDivProp) D.
End NLcmPropPrivate.
Module Type NLcmProp0
(Import A : NAxiomsSig')
(Import B : NSubProp A)
(Import A' : NZDivSpec0 A A A)
(Import D : NGcdProp A B)
(Import C : NDivPropPrivate A B)
(Import C' : NDivProp0 A B A' C)
(Import E : NLcmPropPrivate A B C D).
Definition lcm a b := a*(b/gcd a b).
#[global] Instance lcm_wd : Proper (eq==>eq==>eq) lcm := lcm_wd.
(* The types are restated to avoid [Private_NLcmProp.lcm] indirection. *)
Definition gcd_div_gcd : forall a b g, g ~= 0 -> g == gcd a b ->
gcd (a / g) (b / g) == 1 := gcd_div_gcd.
Definition divide_lcm_l : forall a b, (a | lcm a b) := divide_lcm_l.
Definition gcd_div_swap : forall a b, a / gcd a b * b == a * (b / gcd a b) := gcd_div_swap.
Definition divide_lcm_r : forall a b, (b | lcm a b) := divide_lcm_r.
Definition lcm_least : forall a b c, (a | c) -> (b | c) -> (lcm a b | c) := lcm_least.
Definition lcm_comm : forall a b, lcm a b == lcm b a := lcm_comm.
Definition lcm_divide_iff : forall n m p, (lcm n m | p) <-> (n | p) /\ (m | p) := lcm_divide_iff.
Definition lcm_assoc : forall n m p, lcm n (lcm m p) == lcm (lcm n m) p := lcm_assoc.
Definition lcm_0_l : forall n, lcm 0 n == 0 := lcm_0_l.
Definition lcm_0_r : forall n, lcm n 0 == 0 := lcm_0_r.
Definition lcm_1_l : forall n, lcm 1 n == n := lcm_1_l.
Definition lcm_1_r : forall n, lcm n 1 == n := lcm_1_r.
Definition lcm_diag : forall n : t, lcm n n == n := lcm_diag.
Definition lcm_eq_0 : forall n m, lcm n m == 0 <-> n == 0 \/ m == 0 := lcm_eq_0.
Definition divide_lcm_eq_r : forall n m, (n | m) -> lcm n m == m := divide_lcm_eq_r.
Definition divide_lcm_iff : forall n m, (n | m) <-> lcm n m == m := divide_lcm_iff.
Definition lcm_mul_mono_l : forall n m p, lcm (p * n) (p * m) == p * lcm n m := lcm_mul_mono_l.
Definition lcm_mul_mono_r : forall n m p, lcm (n * p) (m * p) == lcm n m * p := lcm_mul_mono_r.
Definition gcd_1_lcm_mul : forall n m, n ~= 0 -> m ~= 0 ->
gcd n m == 1 <-> lcm n m == n * m := gcd_1_lcm_mul.
Module Lcm0.
#[local] Hint Rewrite div_0_l mod_0_l div_0_r mod_0_r gcd_0_l gcd_0_r : nz.

Lemma gcd_div_factor : forall a b c, (c|a) -> (c|b) ->
gcd (a/c) (b/c) == (gcd a b)/c.