Coq中分号的奇怪行为

我很难理解为什么我的Coq代码没有达到我在下面代码中期望的效果

• 我试图使这个例子尽可能简化，但当我把它简化后，问题就不再出现了
• 它正在使用CompCert 1.8文件
• 这在Coq 8.2-pl2下发生在我身上

代码如下：

Require Import Axioms.
Require Import Coqlib.
Require Import Integers.
Require Import Values.
Require Import Asm.

Definition foo (ofs: int) (c: code) : Prop :=
  c <> nil /\ ofs <> Int.zero.

Inductive some_prop: nat -> Prop :=
| some_prop_ctor :
  forall n other_n ofs c lo hi ofs_ra ofs_link,
    some_prop n ->
    foo ofs c ->
    find_instr (Int.unsigned ofs) c <> Some (Pallocframe lo hi ofs_ra ofs_link) ->
    find_instr (Int.unsigned ofs) c <> Some (Pfreeframe lo hi ofs_ra ofs_link) ->
    some_prop other_n
.

Lemma simplified:
  forall n other_n ofs c,
  some_prop n ->
  foo ofs c ->
  find_instr (Int.unsigned ofs) c = Some Pret ->
  some_prop other_n.
Proof.
  intros.

重写H1时失败，原因是：

Error:
Found no subterm matching "find_instr (Int.unsigned ofs) c" in the current goal.

不过，这是可行的：

  eapply some_prop_ctor
    with (lo:=0) (hi:=0) (ofs_ra:=Int.zero) (ofs_link:=Int.zero);
      eauto.
  rewrite H1; discriminate.
  rewrite H1; discriminate.
Qed.

另外，就在

eauto

之后，我的目标如下：

2 subgoals
n : nat
other_n : nat
ofs : int
c : code
H : some_prop n
H0 : foo ofs c
H1 : find_instr (Int.unsigned ofs) c = Some Pret
______________________________________(1/2)
find_instr (Int.unsigned ofs) c <> Some (Pallocframe 0 0 Int.zero Int.zero)


______________________________________(2/2)
find_instr (Int.unsigned ofs) c <> Some (Pfreeframe 0 0 Int.zero Int.zero)

---

所以，这可能是我自己问题的答案（感谢#coq IRC频道的某个人）：

在这种情况下，存在变量的统一可能要等到

因此，通过分号ing，我可能阻止了

ofs

和

c

的统一

不过我发现写

。。。；欧托；subst；重写H1；区别对待。

将起作用<在这种情况下，code>subst将强制统一存在变量，从而解锁重写的能力

2 subgoals
n : nat
other_n : nat
ofs : int
c : code
H : some_prop n
H0 : foo ofs c
H1 : find_instr (Int.unsigned ofs) c = Some Pret
______________________________________(1/2)
find_instr (Int.unsigned ofs) c <> Some (Pallocframe 0 0 Int.zero Int.zero)


______________________________________(2/2)
find_instr (Int.unsigned ofs) c <> Some (Pfreeframe 0 0 Int.zero Int.zero)

Require Import Axioms.
Require Import Coqlib.
Require Import Integers.
Require Import Values.
Require Import Asm.

Definition foo (ofs: int) (c: code) : Prop :=
  c <> nil /\ ofs <> Int.zero.

Inductive some_prop: nat -> Prop :=
| some_prop_ctor :
  forall n other_n ofs c lo hi ofs_ra ofs_link,
    some_prop n ->
    foo ofs c ->
    find_instr (Int.unsigned ofs) c <> Some (Pallocframe lo hi ofs_ra ofs_link) ->
    find_instr (Int.unsigned ofs) c <> Some (Pfreeframe lo hi ofs_ra ofs_link) ->
    some_prop other_n
.

Lemma simplified:
  forall n other_n ofs c,
  some_prop n ->
  foo ofs c ->
  find_instr (Int.unsigned ofs) c = Some Pret ->
  some_prop other_n.
Proof.
  intros.
(*** This does not work:
  eapply some_prop_ctor
    with (lo:=0) (hi:=0) (ofs_ra:=Int.zero) (ofs_link:=Int.zero);
      eauto; rewrite H1; discriminate.
***)
  eapply some_prop_ctor
    with (lo:=0) (hi:=0) (ofs_ra:=Int.zero) (ofs_link:=Int.zero);
      eauto.    
  rewrite H1; discriminate.
  rewrite H1; discriminate.
Qed.