src/Pure/drule.ML
author nipkow
Wed Mar 04 13:16:05 1998 +0100 (1998-03-04)
changeset 4679 24917efb31b5
parent 4610 b1322be47244
child 4691 b159f5d98ceb
permissions -rw-r--r--
Reorganized simplifier. May now reorient rules.
Moved loop tests from logic to thm.
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(*  Title:      Pure/drule.ML
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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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Derived rules and other operations on theorems.
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*)
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infix 0 RS RSN RL RLN MRS MRL COMP;
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signature DRULE =
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sig
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  val dest_implies      : cterm -> cterm * cterm
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  val skip_flexpairs	: cterm -> cterm
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  val strip_imp_prems	: cterm -> cterm list
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  val cprems_of		: thm -> cterm list
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  val read_insts	:
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          Sign.sg -> (indexname -> typ option) * (indexname -> sort option)
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                  -> (indexname -> typ option) * (indexname -> sort option)
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                  -> string list -> (string*string)list
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                  -> (indexname*ctyp)list * (cterm*cterm)list
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  val types_sorts: thm -> (indexname-> typ option) * (indexname-> sort option)
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  val forall_intr_list	: cterm list -> thm -> thm
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  val forall_intr_frees	: thm -> thm
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  val forall_intr_vars	: thm -> thm
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  val forall_elim_list	: cterm list -> thm -> thm
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  val forall_elim_var	: int -> thm -> thm
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  val forall_elim_vars	: int -> thm -> thm
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  val freeze_thaw	: thm -> thm * (thm -> thm)
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  val implies_elim_list	: thm -> thm list -> thm
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  val implies_intr_list	: cterm list -> thm -> thm
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  val zero_var_indexes	: thm -> thm
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  val standard		: thm -> thm
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  val rotate_prems      : int -> thm -> thm
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  val assume_ax		: theory -> string -> thm
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  val RSN		: thm * (int * thm) -> thm
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  val RS		: thm * thm -> thm
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  val RLN		: thm list * (int * thm list) -> thm list
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  val RL		: thm list * thm list -> thm list
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  val MRS		: thm list * thm -> thm
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  val MRL		: thm list list * thm list -> thm list
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  val compose		: thm * int * thm -> thm list
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  val COMP		: thm * thm -> thm
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  val read_instantiate_sg: Sign.sg -> (string*string)list -> thm -> thm
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  val read_instantiate	: (string*string)list -> thm -> thm
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  val cterm_instantiate	: (cterm*cterm)list -> thm -> thm
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  val weak_eq_thm	: thm * thm -> bool
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  val eq_thm_sg		: thm * thm -> bool
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  val size_of_thm	: thm -> int
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  val reflexive_thm	: thm
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  val symmetric_thm	: thm
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  val transitive_thm	: thm
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  val refl_implies      : thm
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  val symmetric_fun     : thm -> thm
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  val rewrite_rule_aux	: (meta_simpset -> thm -> thm option) -> thm list -> thm -> thm
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  val rewrite_thm	: bool * bool -> (meta_simpset -> thm -> thm option)
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	-> meta_simpset -> thm -> thm
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  val rewrite_goals_rule_aux: (meta_simpset -> thm -> thm option) -> thm list -> thm -> thm
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  val rewrite_goal_rule	: bool * bool -> (meta_simpset -> thm -> thm option)
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        -> meta_simpset -> int -> thm -> thm
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  val equal_abs_elim	: cterm  -> thm -> thm
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  val equal_abs_elim_list: cterm list -> thm -> thm
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  val flexpair_abs_elim_list: cterm list -> thm -> thm
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  val asm_rl		: thm
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  val cut_rl		: thm
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  val revcut_rl		: thm
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  val thin_rl		: thm
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  val triv_forall_equality: thm
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  val swap_prems_rl     : thm
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  val equal_intr_rule   : thm
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  val instantiate': ctyp option list -> cterm option list -> thm -> thm
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end;
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structure Drule : DRULE =
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struct
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(** some cterm->cterm operations: much faster than calling cterm_of! **)
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(** SAME NAMES as in structure Logic: use compound identifiers! **)
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(*dest_implies for cterms. Note T=prop below*)
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fun dest_implies ct =
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    case term_of ct of 
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	(Const("==>", _) $ _ $ _) => 
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	    let val (ct1,ct2) = dest_comb ct
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	    in  (#2 (dest_comb ct1), ct2)  end	     
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      | _ => raise TERM ("dest_implies", [term_of ct]) ;
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(*Discard flexflex pairs; return a cterm*)
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fun skip_flexpairs ct =
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    case term_of ct of
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	(Const("==>", _) $ (Const("=?=",_)$_$_) $ _) =>
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	    skip_flexpairs (#2 (dest_implies ct))
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      | _ => ct;
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(* A1==>...An==>B  goes to  [A1,...,An], where B is not an implication *)
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fun strip_imp_prems ct =
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    let val (cA,cB) = dest_implies ct
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    in  cA :: strip_imp_prems cB  end
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    handle TERM _ => [];
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(* A1==>...An==>B  goes to B, where B is not an implication *)
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fun strip_imp_concl ct =
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    case term_of ct of (Const("==>", _) $ _ $ _) => 
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	strip_imp_concl (#2 (dest_comb ct))
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  | _ => ct;
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(*The premises of a theorem, as a cterm list*)
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val cprems_of = strip_imp_prems o skip_flexpairs o cprop_of;
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(** reading of instantiations **)
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fun indexname cs = case Syntax.scan_varname cs of (v,[]) => v
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        | _ => error("Lexical error in variable name " ^ quote (implode cs));
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fun absent ixn =
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  error("No such variable in term: " ^ Syntax.string_of_vname ixn);
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fun inst_failure ixn =
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  error("Instantiation of " ^ Syntax.string_of_vname ixn ^ " fails");
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fun read_insts sign (rtypes,rsorts) (types,sorts) used insts =
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let val {tsig,...} = Sign.rep_sg sign
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    fun split([],tvs,vs) = (tvs,vs)
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      | split((sv,st)::l,tvs,vs) = (case explode sv of
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                  "'"::cs => split(l,(indexname cs,st)::tvs,vs)
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                | cs => split(l,tvs,(indexname cs,st)::vs));
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    val (tvs,vs) = split(insts,[],[]);
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    fun readT((a,i),st) =
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        let val ixn = ("'" ^ a,i);
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            val S = case rsorts ixn of Some S => S | None => absent ixn;
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            val T = Sign.read_typ (sign,sorts) st;
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        in if Type.typ_instance(tsig,T,TVar(ixn,S)) then (ixn,T)
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           else inst_failure ixn
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        end
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    val tye = map readT tvs;
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    fun mkty(ixn,st) = (case rtypes ixn of
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                          Some T => (ixn,(st,typ_subst_TVars tye T))
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                        | None => absent ixn);
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    val ixnsTs = map mkty vs;
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    val ixns = map fst ixnsTs
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    and sTs  = map snd ixnsTs
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    val (cts,tye2) = read_def_cterms(sign,types,sorts) used false sTs;
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    fun mkcVar(ixn,T) =
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        let val U = typ_subst_TVars tye2 T
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        in cterm_of sign (Var(ixn,U)) end
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    val ixnTs = ListPair.zip(ixns, map snd sTs)
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in (map (fn (ixn,T) => (ixn,ctyp_of sign T)) (tye2 @ tye),
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    ListPair.zip(map mkcVar ixnTs,cts))
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end;
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(*** Find the type (sort) associated with a (T)Var or (T)Free in a term
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     Used for establishing default types (of variables) and sorts (of
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     type variables) when reading another term.
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     Index -1 indicates that a (T)Free rather than a (T)Var is wanted.
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***)
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fun types_sorts thm =
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    let val {prop,hyps,...} = rep_thm thm;
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        val big = list_comb(prop,hyps); (* bogus term! *)
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        val vars = map dest_Var (term_vars big);
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        val frees = map dest_Free (term_frees big);
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        val tvars = term_tvars big;
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        val tfrees = term_tfrees big;
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        fun typ(a,i) = if i<0 then assoc(frees,a) else assoc(vars,(a,i));
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        fun sort(a,i) = if i<0 then assoc(tfrees,a) else assoc(tvars,(a,i));
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    in (typ,sort) end;
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(** Standardization of rules **)
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(*Generalization over a list of variables, IGNORING bad ones*)
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fun forall_intr_list [] th = th
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  | forall_intr_list (y::ys) th =
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        let val gth = forall_intr_list ys th
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        in  forall_intr y gth   handle THM _ =>  gth  end;
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(*Generalization over all suitable Free variables*)
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fun forall_intr_frees th =
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    let val {prop,sign,...} = rep_thm th
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    in  forall_intr_list
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         (map (cterm_of sign) (sort (make_ord atless) (term_frees prop)))
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         th
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    end;
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(*Replace outermost quantified variable by Var of given index.
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    Could clash with Vars already present.*)
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fun forall_elim_var i th =
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    let val {prop,sign,...} = rep_thm th
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    in case prop of
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          Const("all",_) $ Abs(a,T,_) =>
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              forall_elim (cterm_of sign (Var((a,i), T)))  th
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        | _ => raise THM("forall_elim_var", i, [th])
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    end;
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(*Repeat forall_elim_var until all outer quantifiers are removed*)
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fun forall_elim_vars i th =
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    forall_elim_vars i (forall_elim_var i th)
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        handle THM _ => th;
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(*Specialization over a list of cterms*)
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fun forall_elim_list cts th = foldr (uncurry forall_elim) (rev cts, th);
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(* maps [A1,...,An], B   to   [| A1;...;An |] ==> B  *)
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fun implies_intr_list cAs th = foldr (uncurry implies_intr) (cAs,th);
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(* maps [| A1;...;An |] ==> B and [A1,...,An]   to   B *)
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fun implies_elim_list impth ths = foldl (uncurry implies_elim) (impth,ths);
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(*Reset Var indexes to zero, renaming to preserve distinctness*)
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fun zero_var_indexes th =
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    let val {prop,sign,...} = rep_thm th;
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        val vars = term_vars prop
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        val bs = foldl add_new_id ([], map (fn Var((a,_),_)=>a) vars)
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        val inrs = add_term_tvars(prop,[]);
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        val nms' = rev(foldl add_new_id ([], map (#1 o #1) inrs));
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        val tye = ListPair.map (fn ((v,rs),a) => (v, TVar((a,0),rs)))
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	             (inrs, nms')
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        val ctye = map (fn (v,T) => (v,ctyp_of sign T)) tye;
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        fun varpairs([],[]) = []
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          | varpairs((var as Var(v,T)) :: vars, b::bs) =
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                let val T' = typ_subst_TVars tye T
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                in (cterm_of sign (Var(v,T')),
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                    cterm_of sign (Var((b,0),T'))) :: varpairs(vars,bs)
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                end
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          | varpairs _ = raise TERM("varpairs", []);
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    in instantiate (ctye, varpairs(vars,rev bs)) th end;
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(*Standard form of object-rule: no hypotheses, Frees, or outer quantifiers;
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    all generality expressed by Vars having index 0.*)
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fun standard th =
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  let val {maxidx,...} = rep_thm th
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  in
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    th |> implies_intr_hyps
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       |> forall_intr_frees |> forall_elim_vars (maxidx + 1)
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       |> Thm.strip_shyps |> Thm.implies_intr_shyps
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       |> zero_var_indexes |> Thm.varifyT |> Thm.compress
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  end;
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(*Convert all Vars in a theorem to Frees.  Also return a function for 
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  reversing that operation.  DOES NOT WORK FOR TYPE VARIABLES.
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  Similar code in type/freeze_thaw*)
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fun freeze_thaw th =
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  let val fth = freezeT th
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      val {prop,sign,...} = rep_thm fth
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      val used = add_term_names (prop, [])
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      and vars = term_vars prop
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      fun newName (Var(ix,_), (pairs,used)) = 
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	    let val v = variant used (string_of_indexname ix)
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	    in  ((ix,v)::pairs, v::used)  end;
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      val (alist, _) = foldr newName (vars, ([], used))
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      fun mk_inst (Var(v,T)) = 
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	  (cterm_of sign (Var(v,T)),
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	   cterm_of sign (Free(the (assoc(alist,v)), T)))
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      val insts = map mk_inst vars
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      fun thaw th' = 
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	  th' |> forall_intr_list (map #2 insts)
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	      |> forall_elim_list (map #1 insts)
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  in  (instantiate ([],insts) fth, thaw)  end;
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(*Rotates a rule's premises to the left by k.  Does nothing if k=0 or
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  if k equals the number of premises.  Useful, for instance, with etac.
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  Similar to tactic/defer_tac*)
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fun rotate_prems k rl = 
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    let val (rl',thaw) = freeze_thaw rl
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	val hyps = strip_imp_prems (adjust_maxidx (cprop_of rl'))
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	val hyps' = List.drop(hyps, k)
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    in  implies_elim_list rl' (map assume hyps)
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        |> implies_intr_list (hyps' @ List.take(hyps, k))
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        |> thaw |> varifyT
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    end;
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(*Assume a new formula, read following the same conventions as axioms.
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  Generalizes over Free variables,
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  creates the assumption, and then strips quantifiers.
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  Example is [| ALL x:?A. ?P(x) |] ==> [| ?P(?a) |]
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             [ !(A,P,a)[| ALL x:A. P(x) |] ==> [| P(a) |] ]    *)
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fun assume_ax thy sP =
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    let val sign = sign_of thy
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        val prop = Logic.close_form (term_of (read_cterm sign (sP, propT)))
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    in forall_elim_vars 0 (assume (cterm_of sign prop))  end;
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(*Resolution: exactly one resolvent must be produced.*)
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fun tha RSN (i,thb) =
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  case Seq.chop (2, biresolution false [(false,tha)] i thb) of
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      ([th],_) => th
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    | ([],_)   => raise THM("RSN: no unifiers", i, [tha,thb])
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    |      _   => raise THM("RSN: multiple unifiers", i, [tha,thb]);
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(*resolution: P==>Q, Q==>R gives P==>R. *)
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fun tha RS thb = tha RSN (1,thb);
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(*For joining lists of rules*)
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fun thas RLN (i,thbs) =
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  let val resolve = biresolution false (map (pair false) thas) i
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      fun resb thb = Seq.list_of (resolve thb) handle THM _ => []
paulson@2672
   305
  in  List.concat (map resb thbs)  end;
clasohm@0
   306
clasohm@0
   307
fun thas RL thbs = thas RLN (1,thbs);
clasohm@0
   308
lcp@11
   309
(*Resolve a list of rules against bottom_rl from right to left;
lcp@11
   310
  makes proof trees*)
wenzelm@252
   311
fun rls MRS bottom_rl =
lcp@11
   312
  let fun rs_aux i [] = bottom_rl
wenzelm@252
   313
        | rs_aux i (rl::rls) = rl RSN (i, rs_aux (i+1) rls)
lcp@11
   314
  in  rs_aux 1 rls  end;
lcp@11
   315
lcp@11
   316
(*As above, but for rule lists*)
wenzelm@252
   317
fun rlss MRL bottom_rls =
lcp@11
   318
  let fun rs_aux i [] = bottom_rls
wenzelm@252
   319
        | rs_aux i (rls::rlss) = rls RLN (i, rs_aux (i+1) rlss)
lcp@11
   320
  in  rs_aux 1 rlss  end;
lcp@11
   321
wenzelm@252
   322
(*compose Q and [...,Qi,Q(i+1),...]==>R to [...,Q(i+1),...]==>R
clasohm@0
   323
  with no lifting or renaming!  Q may contain ==> or meta-quants
clasohm@0
   324
  ALWAYS deletes premise i *)
wenzelm@252
   325
fun compose(tha,i,thb) =
wenzelm@4270
   326
    Seq.list_of (bicompose false (false,tha,0) i thb);
clasohm@0
   327
clasohm@0
   328
(*compose Q and [Q1,Q2,...,Qk]==>R to [Q2,...,Qk]==>R getting unique result*)
clasohm@0
   329
fun tha COMP thb =
clasohm@0
   330
    case compose(tha,1,thb) of
wenzelm@252
   331
        [th] => th
clasohm@0
   332
      | _ =>   raise THM("COMP", 1, [tha,thb]);
clasohm@0
   333
clasohm@0
   334
(*Instantiate theorem th, reading instantiations under signature sg*)
clasohm@0
   335
fun read_instantiate_sg sg sinsts th =
clasohm@0
   336
    let val ts = types_sorts th;
nipkow@952
   337
        val used = add_term_tvarnames(#prop(rep_thm th),[]);
nipkow@952
   338
    in  instantiate (read_insts sg ts ts used sinsts) th  end;
clasohm@0
   339
clasohm@0
   340
(*Instantiate theorem th, reading instantiations under theory of th*)
clasohm@0
   341
fun read_instantiate sinsts th =
clasohm@0
   342
    read_instantiate_sg (#sign (rep_thm th)) sinsts th;
clasohm@0
   343
clasohm@0
   344
clasohm@0
   345
(*Left-to-right replacements: tpairs = [...,(vi,ti),...].
clasohm@0
   346
  Instantiates distinct Vars by terms, inferring type instantiations. *)
clasohm@0
   347
local
nipkow@1435
   348
  fun add_types ((ct,cu), (sign,tye,maxidx)) =
paulson@2152
   349
    let val {sign=signt, t=t, T= T, maxidx=maxt,...} = rep_cterm ct
paulson@2152
   350
        and {sign=signu, t=u, T= U, maxidx=maxu,...} = rep_cterm cu;
paulson@2152
   351
        val maxi = Int.max(maxidx, Int.max(maxt, maxu));
clasohm@0
   352
        val sign' = Sign.merge(sign, Sign.merge(signt, signu))
nipkow@1435
   353
        val (tye',maxi') = Type.unify (#tsig(Sign.rep_sg sign')) maxi tye (T,U)
wenzelm@252
   354
          handle Type.TUNIFY => raise TYPE("add_types", [T,U], [t,u])
nipkow@1435
   355
    in  (sign', tye', maxi')  end;
clasohm@0
   356
in
wenzelm@252
   357
fun cterm_instantiate ctpairs0 th =
nipkow@1435
   358
  let val (sign,tye,_) = foldr add_types (ctpairs0, (#sign(rep_thm th),[],0))
clasohm@0
   359
      val tsig = #tsig(Sign.rep_sg sign);
clasohm@0
   360
      fun instT(ct,cu) = let val inst = subst_TVars tye
wenzelm@252
   361
                         in (cterm_fun inst ct, cterm_fun inst cu) end
lcp@229
   362
      fun ctyp2 (ix,T) = (ix, ctyp_of sign T)
clasohm@0
   363
  in  instantiate (map ctyp2 tye, map instT ctpairs0) th  end
wenzelm@252
   364
  handle TERM _ =>
clasohm@0
   365
           raise THM("cterm_instantiate: incompatible signatures",0,[th])
wenzelm@4057
   366
       | TYPE (msg, _, _) => raise THM("cterm_instantiate: " ^ msg, 0, [th])
clasohm@0
   367
end;
clasohm@0
   368
clasohm@0
   369
wenzelm@4016
   370
(** theorem equality **)
clasohm@0
   371
clasohm@0
   372
(*Do the two theorems have the same signature?*)
wenzelm@252
   373
fun eq_thm_sg (th1,th2) = Sign.eq_sg(#sign(rep_thm th1), #sign(rep_thm th2));
clasohm@0
   374
clasohm@0
   375
(*Useful "distance" function for BEST_FIRST*)
clasohm@0
   376
val size_of_thm = size_of_term o #prop o rep_thm;
clasohm@0
   377
clasohm@0
   378
lcp@1194
   379
(** Mark Staples's weaker version of eq_thm: ignores variable renaming and
lcp@1194
   380
    (some) type variable renaming **)
lcp@1194
   381
lcp@1194
   382
 (* Can't use term_vars, because it sorts the resulting list of variable names.
lcp@1194
   383
    We instead need the unique list noramlised by the order of appearance
lcp@1194
   384
    in the term. *)
lcp@1194
   385
fun term_vars' (t as Var(v,T)) = [t]
lcp@1194
   386
  | term_vars' (Abs(_,_,b)) = term_vars' b
lcp@1194
   387
  | term_vars' (f$a) = (term_vars' f) @ (term_vars' a)
lcp@1194
   388
  | term_vars' _ = [];
lcp@1194
   389
lcp@1194
   390
fun forall_intr_vars th =
lcp@1194
   391
  let val {prop,sign,...} = rep_thm th;
lcp@1194
   392
      val vars = distinct (term_vars' prop);
lcp@1194
   393
  in forall_intr_list (map (cterm_of sign) vars) th end;
lcp@1194
   394
wenzelm@1237
   395
fun weak_eq_thm (tha,thb) =
lcp@1194
   396
    eq_thm(forall_intr_vars (freezeT tha), forall_intr_vars (freezeT thb));
lcp@1194
   397
lcp@1194
   398
lcp@1194
   399
clasohm@0
   400
(*** Meta-Rewriting Rules ***)
clasohm@0
   401
paulson@4610
   402
val proto_sign = sign_of ProtoPure.thy;
paulson@4610
   403
paulson@4610
   404
fun read_prop s = read_cterm proto_sign (s, propT);
paulson@4610
   405
wenzelm@4016
   406
fun store_thm name thm = PureThy.smart_store_thm (name, standard thm);
wenzelm@4016
   407
clasohm@0
   408
val reflexive_thm =
paulson@4610
   409
  let val cx = cterm_of proto_sign (Var(("x",0),TVar(("'a",0),logicS)))
wenzelm@4016
   410
  in store_thm "reflexive" (Thm.reflexive cx) end;
clasohm@0
   411
clasohm@0
   412
val symmetric_thm =
paulson@4610
   413
  let val xy = read_prop "x::'a::logic == y"
paulson@4610
   414
  in store_thm "symmetric" 
paulson@4610
   415
      (Thm.implies_intr_hyps(Thm.symmetric(Thm.assume xy)))
paulson@4610
   416
   end;
clasohm@0
   417
clasohm@0
   418
val transitive_thm =
paulson@4610
   419
  let val xy = read_prop "x::'a::logic == y"
paulson@4610
   420
      val yz = read_prop "y::'a::logic == z"
clasohm@0
   421
      val xythm = Thm.assume xy and yzthm = Thm.assume yz
paulson@4610
   422
  in store_thm "transitive" (Thm.implies_intr yz (Thm.transitive xythm yzthm))
paulson@4610
   423
  end;
clasohm@0
   424
nipkow@4679
   425
fun symmetric_fun thm = thm RS symmetric_thm;
nipkow@4679
   426
lcp@229
   427
(** Below, a "conversion" has type cterm -> thm **)
lcp@229
   428
paulson@4610
   429
val refl_implies = reflexive (cterm_of proto_sign implies);
clasohm@0
   430
clasohm@0
   431
(*In [A1,...,An]==>B, rewrite the selected A's only -- for rewrite_goals_tac*)
nipkow@214
   432
(*Do not rewrite flex-flex pairs*)
wenzelm@252
   433
fun goals_conv pred cv =
lcp@229
   434
  let fun gconv i ct =
paulson@2004
   435
        let val (A,B) = dest_implies ct
lcp@229
   436
            val (thA,j) = case term_of A of
lcp@229
   437
                  Const("=?=",_)$_$_ => (reflexive A, i)
lcp@229
   438
                | _ => (if pred i then cv A else reflexive A, i+1)
paulson@2004
   439
        in  combination (combination refl_implies thA) (gconv j B) end
lcp@229
   440
        handle TERM _ => reflexive ct
clasohm@0
   441
  in gconv 1 end;
clasohm@0
   442
clasohm@0
   443
(*Use a conversion to transform a theorem*)
lcp@229
   444
fun fconv_rule cv th = equal_elim (cv (cprop_of th)) th;
clasohm@0
   445
clasohm@0
   446
(*rewriting conversion*)
lcp@229
   447
fun rew_conv mode prover mss = rewrite_cterm mode mss prover;
clasohm@0
   448
clasohm@0
   449
(*Rewrite a theorem*)
wenzelm@3575
   450
fun rewrite_rule_aux _ []   th = th
wenzelm@3575
   451
  | rewrite_rule_aux prover thms th =
wenzelm@3575
   452
      fconv_rule (rew_conv (true,false) prover (Thm.mss_of thms)) th;
clasohm@0
   453
wenzelm@3555
   454
fun rewrite_thm mode prover mss = fconv_rule (rew_conv mode prover mss);
wenzelm@3555
   455
clasohm@0
   456
(*Rewrite the subgoals of a proof state (represented by a theorem) *)
wenzelm@3575
   457
fun rewrite_goals_rule_aux _ []   th = th
wenzelm@3575
   458
  | rewrite_goals_rule_aux prover thms th =
wenzelm@3575
   459
      fconv_rule (goals_conv (K true) (rew_conv (true, true) prover
wenzelm@3575
   460
        (Thm.mss_of thms))) th;
clasohm@0
   461
clasohm@0
   462
(*Rewrite the subgoal of a proof state (represented by a theorem) *)
nipkow@214
   463
fun rewrite_goal_rule mode prover mss i thm =
nipkow@214
   464
  if 0 < i  andalso  i <= nprems_of thm
nipkow@214
   465
  then fconv_rule (goals_conv (fn j => j=i) (rew_conv mode prover mss)) thm
nipkow@214
   466
  else raise THM("rewrite_goal_rule",i,[thm]);
clasohm@0
   467
clasohm@0
   468
clasohm@0
   469
(** Derived rules mainly for METAHYPS **)
clasohm@0
   470
clasohm@0
   471
(*Given the term "a", takes (%x.t)==(%x.u) to t[a/x]==u[a/x]*)
clasohm@0
   472
fun equal_abs_elim ca eqth =
lcp@229
   473
  let val {sign=signa, t=a, ...} = rep_cterm ca
clasohm@0
   474
      and combth = combination eqth (reflexive ca)
clasohm@0
   475
      val {sign,prop,...} = rep_thm eqth
clasohm@0
   476
      val (abst,absu) = Logic.dest_equals prop
lcp@229
   477
      val cterm = cterm_of (Sign.merge (sign,signa))
clasohm@0
   478
  in  transitive (symmetric (beta_conversion (cterm (abst$a))))
clasohm@0
   479
           (transitive combth (beta_conversion (cterm (absu$a))))
clasohm@0
   480
  end
clasohm@0
   481
  handle THM _ => raise THM("equal_abs_elim", 0, [eqth]);
clasohm@0
   482
clasohm@0
   483
(*Calling equal_abs_elim with multiple terms*)
clasohm@0
   484
fun equal_abs_elim_list cts th = foldr (uncurry equal_abs_elim) (rev cts, th);
clasohm@0
   485
clasohm@0
   486
local
clasohm@0
   487
  val alpha = TVar(("'a",0), [])     (*  type ?'a::{}  *)
clasohm@0
   488
  fun err th = raise THM("flexpair_inst: ", 0, [th])
clasohm@0
   489
  fun flexpair_inst def th =
clasohm@0
   490
    let val {prop = Const _ $ t $ u,  sign,...} = rep_thm th
wenzelm@252
   491
        val cterm = cterm_of sign
wenzelm@252
   492
        fun cvar a = cterm(Var((a,0),alpha))
wenzelm@252
   493
        val def' = cterm_instantiate [(cvar"t", cterm t), (cvar"u", cterm u)]
wenzelm@252
   494
                   def
clasohm@0
   495
    in  equal_elim def' th
clasohm@0
   496
    end
clasohm@0
   497
    handle THM _ => err th | bind => err th
clasohm@0
   498
in
wenzelm@3991
   499
val flexpair_intr = flexpair_inst (symmetric ProtoPure.flexpair_def)
wenzelm@3991
   500
and flexpair_elim = flexpair_inst ProtoPure.flexpair_def
clasohm@0
   501
end;
clasohm@0
   502
clasohm@0
   503
(*Version for flexflex pairs -- this supports lifting.*)
wenzelm@252
   504
fun flexpair_abs_elim_list cts =
clasohm@0
   505
    flexpair_intr o equal_abs_elim_list cts o flexpair_elim;
clasohm@0
   506
clasohm@0
   507
clasohm@0
   508
(*** Some useful meta-theorems ***)
clasohm@0
   509
clasohm@0
   510
(*The rule V/V, obtains assumption solving for eresolve_tac*)
wenzelm@4016
   511
val asm_rl =
paulson@4610
   512
  store_thm "asm_rl" (trivial(read_prop "PROP ?psi"));
clasohm@0
   513
clasohm@0
   514
(*Meta-level cut rule: [| V==>W; V |] ==> W *)
wenzelm@4016
   515
val cut_rl =
wenzelm@4016
   516
  store_thm "cut_rl"
paulson@4610
   517
    (trivial(read_prop "PROP ?psi ==> PROP ?theta"));
clasohm@0
   518
wenzelm@252
   519
(*Generalized elim rule for one conclusion; cut_rl with reversed premises:
clasohm@0
   520
     [| PROP V;  PROP V ==> PROP W |] ==> PROP W *)
clasohm@0
   521
val revcut_rl =
paulson@4610
   522
  let val V = read_prop "PROP V"
paulson@4610
   523
      and VW = read_prop "PROP V ==> PROP W";
wenzelm@4016
   524
  in
wenzelm@4016
   525
    store_thm "revcut_rl"
wenzelm@4016
   526
      (implies_intr V (implies_intr VW (implies_elim (assume VW) (assume V))))
clasohm@0
   527
  end;
clasohm@0
   528
lcp@668
   529
(*for deleting an unwanted assumption*)
lcp@668
   530
val thin_rl =
paulson@4610
   531
  let val V = read_prop "PROP V"
paulson@4610
   532
      and W = read_prop "PROP W";
wenzelm@4016
   533
  in  store_thm "thin_rl" (implies_intr V (implies_intr W (assume W)))
lcp@668
   534
  end;
lcp@668
   535
clasohm@0
   536
(* (!!x. PROP ?V) == PROP ?V       Allows removal of redundant parameters*)
clasohm@0
   537
val triv_forall_equality =
paulson@4610
   538
  let val V  = read_prop "PROP V"
paulson@4610
   539
      and QV = read_prop "!!x::'a. PROP V"
paulson@4610
   540
      and x  = read_cterm proto_sign ("x", TFree("'a",logicS));
wenzelm@4016
   541
  in
wenzelm@4016
   542
    store_thm "triv_forall_equality"
wenzelm@4016
   543
      (equal_intr (implies_intr QV (forall_elim x (assume QV)))
wenzelm@4016
   544
        (implies_intr V  (forall_intr x (assume V))))
clasohm@0
   545
  end;
clasohm@0
   546
nipkow@1756
   547
(* (PROP ?PhiA ==> PROP ?PhiB ==> PROP ?Psi) ==>
nipkow@1756
   548
   (PROP ?PhiB ==> PROP ?PhiA ==> PROP ?Psi)
nipkow@1756
   549
   `thm COMP swap_prems_rl' swaps the first two premises of `thm'
nipkow@1756
   550
*)
nipkow@1756
   551
val swap_prems_rl =
paulson@4610
   552
  let val cmajor = read_prop "PROP PhiA ==> PROP PhiB ==> PROP Psi";
nipkow@1756
   553
      val major = assume cmajor;
paulson@4610
   554
      val cminor1 = read_prop "PROP PhiA";
nipkow@1756
   555
      val minor1 = assume cminor1;
paulson@4610
   556
      val cminor2 = read_prop "PROP PhiB";
nipkow@1756
   557
      val minor2 = assume cminor2;
wenzelm@4016
   558
  in store_thm "swap_prems_rl"
nipkow@1756
   559
       (implies_intr cmajor (implies_intr cminor2 (implies_intr cminor1
nipkow@1756
   560
         (implies_elim (implies_elim major minor1) minor2))))
nipkow@1756
   561
  end;
nipkow@1756
   562
nipkow@3653
   563
(* [| PROP ?phi ==> PROP ?psi; PROP ?psi ==> PROP ?phi |]
nipkow@3653
   564
   ==> PROP ?phi == PROP ?psi
paulson@4610
   565
   Introduction rule for == as a meta-theorem.  
nipkow@3653
   566
*)
nipkow@3653
   567
val equal_intr_rule =
paulson@4610
   568
  let val PQ = read_prop "PROP phi ==> PROP psi"
paulson@4610
   569
      and QP = read_prop "PROP psi ==> PROP phi"
wenzelm@4016
   570
  in
wenzelm@4016
   571
    store_thm "equal_intr_rule"
wenzelm@4016
   572
      (implies_intr PQ (implies_intr QP (equal_intr (assume PQ) (assume QP))))
nipkow@3653
   573
  end;
nipkow@3653
   574
wenzelm@4285
   575
wenzelm@4285
   576
wenzelm@4285
   577
(** instantiate' rule **)
wenzelm@4285
   578
wenzelm@4285
   579
(* collect vars *)
wenzelm@4285
   580
wenzelm@4285
   581
val add_tvarsT = foldl_atyps (fn (vs, TVar v) => v ins vs | (vs, _) => vs);
wenzelm@4285
   582
val add_tvars = foldl_types add_tvarsT;
wenzelm@4285
   583
val add_vars = foldl_aterms (fn (vs, Var v) => v ins vs | (vs, _) => vs);
wenzelm@4285
   584
wenzelm@4285
   585
fun tvars_of thm = rev (add_tvars ([], #prop (Thm.rep_thm thm)));
wenzelm@4285
   586
fun vars_of thm = rev (add_vars ([], #prop (Thm.rep_thm thm)));
wenzelm@4285
   587
wenzelm@4285
   588
wenzelm@4285
   589
(* instantiate by left-to-right occurrence of variables *)
wenzelm@4285
   590
wenzelm@4285
   591
fun instantiate' cTs cts thm =
wenzelm@4285
   592
  let
wenzelm@4285
   593
    fun err msg =
wenzelm@4285
   594
      raise TYPE ("instantiate': " ^ msg,
wenzelm@4285
   595
        mapfilter (apsome Thm.typ_of) cTs,
wenzelm@4285
   596
        mapfilter (apsome Thm.term_of) cts);
wenzelm@4285
   597
wenzelm@4285
   598
    fun inst_of (v, ct) =
wenzelm@4285
   599
      (Thm.cterm_of (#sign (Thm.rep_cterm ct)) (Var v), ct)
wenzelm@4285
   600
        handle TYPE (msg, _, _) => err msg;
wenzelm@4285
   601
wenzelm@4285
   602
    fun zip_vars _ [] = []
wenzelm@4285
   603
      | zip_vars (_ :: vs) (None :: opt_ts) = zip_vars vs opt_ts
wenzelm@4285
   604
      | zip_vars (v :: vs) (Some t :: opt_ts) = (v, t) :: zip_vars vs opt_ts
wenzelm@4285
   605
      | zip_vars [] _ = err "more instantiations than variables in thm";
wenzelm@4285
   606
wenzelm@4285
   607
    (*instantiate types first!*)
wenzelm@4285
   608
    val thm' =
wenzelm@4285
   609
      if forall is_none cTs then thm
wenzelm@4285
   610
      else Thm.instantiate (zip_vars (map fst (tvars_of thm)) cTs, []) thm;
wenzelm@4285
   611
    in
wenzelm@4285
   612
      if forall is_none cts then thm'
wenzelm@4285
   613
      else Thm.instantiate ([], map inst_of (zip_vars (vars_of thm') cts)) thm'
wenzelm@4285
   614
    end;
wenzelm@4285
   615
wenzelm@4285
   616
clasohm@0
   617
end;
wenzelm@252
   618
paulson@1499
   619
open Drule;