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(* Title: ZF/ex/acc
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ID: $Id$
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Author: Lawrence C Paulson, Cambridge University Computer Laboratory
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Copyright 1993 University of Cambridge
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Inductive definition of acc(r)
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See Ch. Paulin-Mohring, Inductive Definitions in the System Coq.
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Research Report 92-49, LIP, ENS Lyon. Dec 1992.
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*)
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structure Acc = Inductive_Fun
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(val thy = WF.thy addconsts [(["acc"],"i=>i")];
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val rec_doms = [("acc", "field(r)")];
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val sintrs =
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95
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["[| r-``{a} : Pow(acc(r)); a : field(r) |] ==> a : acc(r)"];
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0
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val monos = [Pow_mono];
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val con_defs = [];
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val type_intrs = [];
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val type_elims = []);
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goal Acc.thy "!!a b r. [| b: acc(r); <a,b>: r |] ==> a: acc(r)";
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by (etac Acc.elim 1);
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by (fast_tac ZF_cs 1);
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val acc_downward = result();
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val [major] = goal Acc.thy "field(r) <= acc(r) ==> wf(r)";
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by (rtac (major RS wfI2) 1);
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by (rtac subsetI 1);
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by (etac Acc.induct 1);
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by (etac (bspec RS mp) 1);
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by (resolve_tac Acc.intrs 1);
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by (assume_tac 2);
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by (ALLGOALS (fast_tac ZF_cs));
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val acc_wfI = result();
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goal ZF.thy "!!r A. field(r Int A*A) <= field(r) Int A";
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by (fast_tac ZF_cs 1);
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val field_Int_prodself = result();
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goal Acc.thy "wf(r Int (acc(r)*acc(r)))";
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by (rtac (field_Int_prodself RS wfI2) 1);
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by (rtac subsetI 1);
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by (etac IntE 1);
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by (etac Acc.induct 1);
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by (etac (bspec RS mp) 1);
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by (rtac IntI 1);
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by (assume_tac 1);
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by (resolve_tac Acc.intrs 1);
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by (assume_tac 2);
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by (ALLGOALS (fast_tac ZF_cs));
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val wf_acc_Int = result();
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val [major] = goal Acc.thy "wf(r) ==> field(r) <= acc(r)";
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by (rtac subsetI 1);
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by (etac (major RS wf_induct2) 1);
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by (rtac subset_refl 1);
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by (resolve_tac Acc.intrs 1);
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by (assume_tac 2);
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by (fast_tac ZF_cs 1);
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val acc_wfD = result();
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goal Acc.thy "wf(r) <-> field(r) <= acc(r)";
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by (EVERY1 [rtac iffI, etac acc_wfD, etac acc_wfI]);
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val wf_acc_iff = result();
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