在对列表上证明子集关系的一个属性 [英] Proving a property of Subset relation on list of pairs
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问题描述
我正在证明有关子集的简单数学属性,例如:A子集B;这与以下事实有关:将成员添加到集合B不会影响此关系。在程序中,A和B是对的列表。 entity_IN_listPair
检查特定对是否在配对列表中,而 listPairEqual
检查两个配对对是否相等。我有点卡住了如何进行引理的证明引理addtolistPairSUB
:
I'm proving a simple mathematical property about subsets, for example : A subset B; which is about the fact that adding a member to set B cannot affect this relation. In the program, A and B are list of pairs. entity_IN_listPair
checks if a specific pair is in a list of pair and listPairEqual
checks equality of two list of pairs. I am a bit stuck how to proceed in the proof of lemma Lemma addtolistPairSUB
:
Require Import List.
Require Import Bool.
Definition entity := nat.
Definition entityID := nat.
Definition listPair : Set :=
list (entity * entityID).
(* Nat equality *)
Fixpoint Entity_eq (X:_) (a b:_) : bool :=
match a with
| O => match b with
| O => true
| S m' => false
end
| S n' => match b with
| O => false
| S m' => ( Entity_eq nat (n')( m'))
end
end.
(* checking if an entity is in an listPair *)
Fixpoint entity_IN_listPair
(entit: entity ) (lispair: listPair) : bool :=
match lispair with
|first::body => match first with
|(p_one,ptwo)=> (Entity_eq (nat)(entit)(p_one ))
|| entity_IN_listPair entit body
end
|nil => false
end.
(* checking the equality of two listPair *)
Fixpoint listPairSUB
(first second: listPair) : bool :=
match first with
|head::tail => match head with
|(part1,part2)=> if (entity_IN_listPair part1 second)
then listPairSUB tail second
else false
end
|nil => true
end.
Definition listPairEqual (firstL secondL:listPair) :=
(listPairSUB firstL secondL) && (listPairSUB secondL firstL).
Lemma addtolistPairSUB:
forall (a b: listPair ) (c:entity * entityID),
listPairSUB a b = true->listPairSUB (a) (c::b) = true .
Proof.
induction a.
推荐答案
在这里。 (我自由地重构了您的代码。)
Here it is. (I took the liberty of refactoring your code a little bit.)
Require Import List.
Require Import Bool.
Definition entity := nat.
Definition entityID := nat.
Definition listPair : Set :=
list (entity * entityID).
Fixpoint in_listpair e (l : listPair) :=
match l with
| nil => false
| (x, y) :: l' => Nat.eqb e x || in_listpair e l'
end.
Fixpoint subset_listpair (l1 l2 : listPair) :=
match l1 with
| nil => true
| (x1, _) :: l1 => in_listpair x1 l2 && subset_listpair l1 l2
end.
Lemma subset_listpair_cons l1 l2 p :
subset_listpair l1 l2 = true ->
subset_listpair l1 (p :: l2) = true.
Proof.
induction l1 as [|[x1 y1] l1 IH]; simpl; trivial.
destruct p as [x2 y2]; simpl.
destruct (in_listpair x1 l2); simpl; try easy.
intros H; rewrite IH; trivial.
now rewrite orb_true_r.
Qed.
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