src/FOLP/ex/Foundation.thy
 author wenzelm Sun, 27 Jan 2008 20:04:32 +0100 changeset 25991 31b38a39e589 child 35762 af3ff2ba4c54 permissions -rw-r--r--
eliminated some legacy ML files;
```
(*  Title:      FOLP/ex/Foundation.ML
ID:         \$Id\$
Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright   1991  University of Cambridge
*)

header "Intuitionistic FOL: Examples from The Foundation of a Generic Theorem Prover"

theory Foundation
imports IFOLP
begin

lemma "?p : A&B  --> (C-->A&C)"
apply (rule impI)
apply (rule impI)
apply (rule conjI)
prefer 2 apply assumption
apply (rule conjunct1)
apply assumption
done

text {*A form of conj-elimination*}
lemma
assumes "p : A & B"
and "!!x y. x : A ==> y : B ==> f(x, y) : C"
shows "?p : C"
apply (rule prems)
apply (rule conjunct1)
apply (rule prems)
apply (rule conjunct2)
apply (rule prems)
done

lemma
assumes "!!A x. x : ~ ~A ==> cla(x) : A"
shows "?p : B | ~B"
apply (rule prems)
apply (rule notI)
apply (rule_tac P = "~B" in notE)
apply (rule_tac  notI)
apply (rule_tac  P = "B | ~B" in notE)
prefer 2 apply assumption
apply (rule_tac  disjI1)
prefer 2 apply assumption
apply (rule notI)
apply (rule_tac P = "B | ~B" in notE)
apply assumption
apply (rule disjI2)
apply assumption
done

lemma
assumes "!!A x. x : ~ ~A ==> cla(x) : A"
shows "?p : B | ~B"
apply (rule prems)
apply (rule notI)
apply (rule notE)
apply (rule_tac  notI)
apply (erule_tac  notE)
apply (erule_tac  disjI1)
apply (rule notI)
apply (erule notE)
apply (erule disjI2)
done

lemma
assumes "p : A | ~A"
and "q : ~ ~A"
shows "?p : A"
apply (rule disjE)
apply (rule prems)
apply assumption
apply (rule FalseE)
apply (rule_tac P = "~A" in notE)
apply (rule prems)
apply assumption
done

subsection "Examples with quantifiers"

lemma
assumes "p : ALL z. G(z)"
shows "?p : ALL z. G(z)|H(z)"
apply (rule allI)
apply (rule disjI1)
apply (rule prems [THEN spec])
done

lemma "?p : ALL x. EX y. x=y"
apply (rule allI)
apply (rule exI)
apply (rule refl)
done

lemma "?p : EX y. ALL x. x=y"
apply (rule exI)
apply (rule allI)
apply (rule refl)?
oops

text {* Parallel lifting example. *}
lemma "?p : EX u. ALL x. EX v. ALL y. EX w. P(u,x,v,y,w)"
apply (rule exI allI)
apply (rule exI allI)
apply (rule exI allI)
apply (rule exI allI)
apply (rule exI allI)
oops

lemma
assumes "p : (EX z. F(z)) & B"
shows "?p : EX z. F(z) & B"
apply (rule conjE)
apply (rule prems)
apply (rule exE)
apply assumption
apply (rule exI)
apply (rule conjI)
apply assumption
apply assumption
done

text {* A bigger demonstration of quantifiers -- not in the paper. *}
lemma "?p : (EX y. ALL x. Q(x,y)) -->  (ALL x. EX y. Q(x,y))"
apply (rule impI)
apply (rule allI)
apply (rule exE, assumption)
apply (rule exI)
apply (rule allE, assumption)
apply assumption
done

end
```