blob: c94d298cdbd60d6425f851666fbe8424d1e1684f (
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
|
// Example from the Boogie 2 language report
type Wicket;
const unique a: Wicket extends complete;
const unique b: Wicket;
const unique c: Wicket extends a, b complete;
const unique d: Wicket extends c;
const unique e: Wicket;
procedure P() returns () {
assert !(exists x:Wicket :: a <: x && a != x);
assert (forall x:Wicket :: x <: a ==> x == a || x <: c);
assert c <: b && !(exists x:Wicket :: c <: x && x <: b && x != c && x != b);
assert !(b <: a) && !(b <: c);
assert c <: a && c <: b && d <: c;
assert (forall x:Wicket :: c <: x ==> c==x || a <: x || b <: x);
assert (forall x:Wicket :: x <: c ==> c==x || x <: d);
assert d <: c;
assert !(a <: d) && !(b <: d) && !(c <: d);
assert false; // unprovable
}
procedure Q() returns () {
assert (forall x:Wicket :: x <: b && x != b ==> x <: c); // unprovable
assert !(exists x:Wicket :: b <: x && b != x); // unprovable
}
|
