aboutsummaryrefslogtreecommitdiffhomepage
path: root/theories/Relations/Relation_Definitions.v
blob: 977135fab73c11aeb61f38585e33e4519c1c5f42 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
(************************************************************************)
(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
(*   \VV/  **************************************************************)
(*    //   *      This file is distributed under the terms of the       *)
(*         *       GNU Lesser General Public License Version 2.1        *)
(************************************************************************)

(*i $Id$ i*)

Section Relation_Definition.

  Variable A : Type.
  
  Definition relation := A -> A -> Prop.

  Variable R : relation.
   

  Section General_Properties_of_Relations.
    
    Definition reflexive : Prop := forall x:A, R x x.
    Definition transitive : Prop := forall x y z:A, R x y -> R y z -> R x z.
    Definition symmetric : Prop := forall x y:A, R x y -> R y x.
    Definition antisymmetric : Prop := forall x y:A, R x y -> R y x -> x = y.

    (* for compatibility with Equivalence in  ../PROGRAMS/ALG/  *)
    Definition equiv := reflexive /\ transitive /\ symmetric.

  End General_Properties_of_Relations.



  Section Sets_of_Relations.
    
    Record preorder : Prop := 
      { preord_refl : reflexive; preord_trans : transitive}.
    
    Record order : Prop := 
      { ord_refl : reflexive;
	ord_trans : transitive;
	ord_antisym : antisymmetric}.
    
    Record equivalence : Prop := 
      { equiv_refl : reflexive;
	equiv_trans : transitive;
	equiv_sym : symmetric}.
    
    Record PER : Prop :=  {per_sym : symmetric; per_trans : transitive}.

  End Sets_of_Relations.


  Section Relations_of_Relations.
    
    Definition inclusion (R1 R2:relation) : Prop :=
      forall x y:A, R1 x y -> R2 x y.
    
    Definition same_relation (R1 R2:relation) : Prop :=
      inclusion R1 R2 /\ inclusion R2 R1.
    
    Definition commut (R1 R2:relation) : Prop :=
      forall x y:A,
	R1 y x -> forall z:A, R2 z y ->  exists2 y' : A, R2 y' x & R1 z y'.

  End Relations_of_Relations.


End Relation_Definition.

Hint Unfold reflexive transitive antisymmetric symmetric: sets v62.

Hint Resolve Build_preorder Build_order Build_equivalence Build_PER
  preord_refl preord_trans ord_refl ord_trans ord_antisym equiv_refl
  equiv_trans equiv_sym per_sym per_trans: sets v62.

Hint Unfold inclusion same_relation commut: sets v62.