--- a/src/Doc/ZF/IFOL_examples.thy Sat Apr 05 17:52:29 2014 +0100
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,58 +0,0 @@
-header{*Examples of Intuitionistic Reasoning*}
-
-theory IFOL_examples imports "~~/src/FOL/IFOL" begin
-
-text{*Quantifier example from the book Logic and Computation*}
-lemma "(EX y. ALL x. Q(x,y)) --> (ALL x. EX y. Q(x,y))"
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (rule impI)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (rule allI)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (rule exI)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (erule exE)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (erule allE)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-txt{*Now @{text "apply assumption"} fails*}
-oops
-
-text{*Trying again, with the same first two steps*}
-lemma "(EX y. ALL x. Q(x,y)) --> (ALL x. EX y. Q(x,y))"
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (rule impI)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (rule allI)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (erule exE)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (rule exI)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (erule allE)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply assumption
- --{* @{subgoals[display,indent=0,margin=65]} *}
-done
-
-lemma "(EX y. ALL x. Q(x,y)) --> (ALL x. EX y. Q(x,y))"
-by (tactic {*IntPr.fast_tac @{context} 1*})
-
-text{*Example of Dyckhoff's method*}
-lemma "~ ~ ((P-->Q) | (Q-->P))"
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (unfold not_def)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (rule impI)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (erule disj_impE)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply (erule imp_impE)
- --{* @{subgoals[display,indent=0,margin=65]} *}
- apply (erule imp_impE)
- --{* @{subgoals[display,indent=0,margin=65]} *}
-apply assumption
-apply (erule FalseE)+
-done
-
-end