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-rw-r--r--Test/dafny0/CoPredicates.dfy59
1 files changed, 0 insertions, 59 deletions
diff --git a/Test/dafny0/CoPredicates.dfy b/Test/dafny0/CoPredicates.dfy
deleted file mode 100644
index c5651c90..00000000
--- a/Test/dafny0/CoPredicates.dfy
+++ /dev/null
@@ -1,59 +0,0 @@
-codatatype Stream<T> = Cons(head: T, tail: Stream);
-
-function Upward(n: int): Stream<int>
-{
- Cons(n, Upward(n + 1))
-}
-
-copredicate Pos(s: Stream<int>)
-{
- 0 < s.head && Pos(s.tail)
-}
-
-copredicate X(s: Stream)
-{
- X(s)
-}
-
-ghost method AlwaysLemma(s: Stream)
- ensures X(s);
-{
-}
-
-function Doubles(n: int): Stream<int>
-{
- Cons(2*n, Doubles(n + 1))
-}
-
-copredicate Even(s: Stream<int>)
-{
- s.head % 2 == 0 && Even(s.tail)
-}
-
-ghost method Lemma0(n: int)
- ensures Even(Doubles(n));
-{
-}
-
-function UpwardBy2(n: int): Stream<int>
-{
- Cons(n, UpwardBy2(n + 2))
-}
-
-ghost method Lemma1(n: int)
- ensures Even(UpwardBy2(2*n)); // error: this is true, but Dafny can't prove it
-{
-}
-
-function U2(n: int): Stream<int>
- requires n % 2 == 0;
-{
- UpwardBy2(n)
-}
-
-// Postponed:
-//ghost method Lemma2(n: int)
-// ensures Even(UpwardBy2(2*n)); // this is true, and Dafny can prove it
-//{
-// assert Even(U2(2*n)); // ... thanks to this lemma
-//}