author paulson Fri, 31 Jan 1997 17:15:55 +0100 changeset 2573 f3e04805895a parent 2572 8a47f85e7a03 child 2574 3a832a3c6376
Correction to Problem 24 (with unsatisfactory proof)
 src/FOL/ex/int.ML file | annotate | diff | comparison | revisions src/FOLP/ex/int.ML file | annotate | diff | comparison | revisions
```--- a/src/FOL/ex/int.ML	Fri Jan 31 17:13:19 1997 +0100
+++ b/src/FOL/ex/int.ML	Fri Jan 31 17:15:55 1997 +0100
@@ -260,7 +260,7 @@

writeln"Problem 21";
goal IFOL.thy "(EX x. P-->Q(x)) & (EX x. Q(x)-->P) --> ~~(EX x. P<->Q(x))";
-(*NOT PROVED*)
+(*NOT PROVED; needs quantifier duplication*)

writeln"Problem 22";
goal IFOL.thy "(ALL x. P <-> Q(x))  -->  (P <-> (ALL x. Q(x)))";
@@ -274,8 +274,12 @@

writeln"Problem 24";
goal IFOL.thy "~(EX x. S(x)&Q(x)) & (ALL x. P(x) --> Q(x)|R(x)) &  \
-\    ~(EX x.P(x)) --> (EX x.Q(x)) & (ALL x. Q(x)|R(x) --> S(x))  \
-\   --> (EX x. P(x)&R(x))";
+\    (~(EX x.P(x)) --> (EX x.Q(x))) & (ALL x. Q(x)|R(x) --> S(x))  \
+\   --> ~~(EX x. P(x)&R(x))";
+(*Not clear why fast_tac, best_tac, ASTAR and ITER_DEEPEN all take forever*)
+by Int.safe_tac;
+by (etac impE 1);
+by (Int.fast_tac 1);
by (Int.fast_tac 1);
result();
```
```--- a/src/FOLP/ex/int.ML	Fri Jan 31 17:13:19 1997 +0100
+++ b/src/FOLP/ex/int.ML	Fri Jan 31 17:15:55 1997 +0100
@@ -264,8 +264,12 @@

writeln"Problem 24";
goal IFOLP.thy "?p : ~(EX x. S(x)&Q(x)) & (ALL x. P(x) --> Q(x)|R(x)) &  \
-\    ~(EX x.P(x)) --> (EX x.Q(x)) & (ALL x. Q(x)|R(x) --> S(x))  \
-\   --> (EX x. P(x)&R(x))";
+\    (~(EX x.P(x)) --> (EX x.Q(x))) & (ALL x. Q(x)|R(x) --> S(x))  \
+\   --> ~~(EX x. P(x)&R(x))";
+(*Not clear why fast_tac, best_tac, ASTAR and ITER_DEEPEN all take forever*)
+by Int.safe_tac;
+by (etac impE 1);
+by (Int.fast_tac 1);
by (Int.fast_tac 1);
result();
```