src/HOL/Decision_Procs/cooper_tac.ML
author wenzelm
Sat Dec 14 17:28:05 2013 +0100 (2013-12-14)
changeset 54742 7a86358a3c0b
parent 52131 366fa32ee2a3
child 55495 b389f65edc44
permissions -rw-r--r--
proper context for basic Simplifier operations: rewrite_rule, rewrite_goals_rule, rewrite_goals_tac etc.;
clarified tool context in some boundary cases;
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(*  Title:      HOL/Decision_Procs/cooper_tac.ML
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    Author:     Amine Chaieb, TU Muenchen
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*)
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signature COOPER_TAC =
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sig
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  val trace: bool Unsynchronized.ref
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  val linz_tac: Proof.context -> bool -> int -> tactic
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end
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structure Cooper_Tac: COOPER_TAC =
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struct
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val trace = Unsynchronized.ref false;
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fun trace_msg s = if !trace then tracing s else ();
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val cooper_ss = simpset_of @{context};
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val nT = HOLogic.natT;
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val comp_arith = @{thms simp_thms}
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val zdvd_int = @{thm zdvd_int};
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val zdiff_int_split = @{thm zdiff_int_split};
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val all_nat = @{thm all_nat};
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val ex_nat = @{thm ex_nat};
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val split_zdiv = @{thm split_zdiv};
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val split_zmod = @{thm split_zmod};
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val mod_div_equality' = @{thm mod_div_equality'};
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val split_div' = @{thm split_div'};
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val Suc_eq_plus1 = @{thm Suc_eq_plus1};
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val imp_le_cong = @{thm imp_le_cong};
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val conj_le_cong = @{thm conj_le_cong};
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val mod_add_left_eq = @{thm mod_add_left_eq} RS sym;
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val mod_add_right_eq = @{thm mod_add_right_eq} RS sym;
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val mod_add_eq = @{thm mod_add_eq} RS sym;
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val nat_div_add_eq = @{thm div_add1_eq} RS sym;
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val int_div_add_eq = @{thm zdiv_zadd1_eq} RS sym;
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fun prepare_for_linz q fm =
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  let
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    val ps = Logic.strip_params fm
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    val hs = map HOLogic.dest_Trueprop (Logic.strip_assums_hyp fm)
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    val c = HOLogic.dest_Trueprop (Logic.strip_assums_concl fm)
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    fun mk_all ((s, T), (P,n)) =
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      if Term.is_dependent P then
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        (HOLogic.all_const T $ Abs (s, T, P), n)
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      else (incr_boundvars ~1 P, n-1)
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    fun mk_all2 (v, t) = HOLogic.all_const (fastype_of v) $ lambda v t;
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    val rhs = hs
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    val np = length ps
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    val (fm',np) = List.foldr (fn ((x, T), (fm,n)) => mk_all ((x, T), (fm,n)))
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      (List.foldr HOLogic.mk_imp c rhs, np) ps
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    val (vs, _) = List.partition (fn t => q orelse (type_of t) = nT)
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      (Misc_Legacy.term_frees fm' @ Misc_Legacy.term_vars fm');
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    val fm2 = List.foldr mk_all2 fm' vs
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  in (fm2, np + length vs, length rhs) end;
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(*Object quantifier to meta --*)
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fun spec_step n th = if (n=0) then th else (spec_step (n-1) th) RS spec ;
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(* object implication to meta---*)
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fun mp_step n th = if (n=0) then th else (mp_step (n-1) th) RS mp;
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fun linz_tac ctxt q = Object_Logic.atomize_prems_tac ctxt THEN' SUBGOAL (fn (g, i) =>
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  let
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    val thy = Proof_Context.theory_of ctxt
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    (* Transform the term*)
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    val (t,np,nh) = prepare_for_linz q g
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    (* Some simpsets for dealing with mod div abs and nat*)
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    val mod_div_simpset =
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      put_simpset HOL_basic_ss ctxt
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      addsimps [refl,mod_add_eq, mod_add_left_eq,
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          mod_add_right_eq,
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          nat_div_add_eq, int_div_add_eq,
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          @{thm mod_self},
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          @{thm div_by_0}, @{thm mod_by_0}, @{thm div_0}, @{thm mod_0},
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          @{thm div_by_1}, @{thm mod_by_1}, @{thm div_1}, @{thm mod_1},
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          Suc_eq_plus1]
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      addsimps @{thms add_ac}
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      addsimprocs [@{simproc cancel_div_mod_nat}, @{simproc cancel_div_mod_int}]
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    val simpset0 =
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      put_simpset HOL_basic_ss ctxt
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      addsimps [mod_div_equality', Suc_eq_plus1]
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      addsimps comp_arith
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      |> fold Splitter.add_split
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          [split_zdiv, split_zmod, split_div', @{thm "split_min"}, @{thm "split_max"}]
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    (* Simp rules for changing (n::int) to int n *)
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    val simpset1 =
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      put_simpset HOL_basic_ss ctxt
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      addsimps [zdvd_int] @ map (fn r => r RS sym)
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        [@{thm int_numeral}, @{thm int_int_eq}, @{thm zle_int}, @{thm zless_int}, @{thm zadd_int}, @{thm zmult_int}]
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      |> Splitter.add_split zdiff_int_split
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    (*simp rules for elimination of int n*)
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    val simpset2 =
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      put_simpset HOL_basic_ss ctxt
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      addsimps [@{thm nat_0_le}, @{thm all_nat}, @{thm ex_nat}, @{thm zero_le_numeral}, @{thm order_refl}(* FIXME: necessary? *), @{thm int_0}, @{thm int_1}]
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      |> fold Simplifier.add_cong [@{thm conj_le_cong}, @{thm imp_le_cong}]
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    (* simp rules for elimination of abs *)
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    val simpset3 = put_simpset HOL_basic_ss ctxt |> Splitter.add_split @{thm abs_split}
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    val ct = cterm_of thy (HOLogic.mk_Trueprop t)
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    (* Theorem for the nat --> int transformation *)
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    val pre_thm = Seq.hd (EVERY
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      [simp_tac mod_div_simpset 1, simp_tac simpset0 1,
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       TRY (simp_tac simpset1 1), TRY (simp_tac simpset2 1),
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       TRY (simp_tac simpset3 1), TRY (simp_tac (put_simpset cooper_ss ctxt) 1)]
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      (Thm.trivial ct))
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    fun assm_tac i = REPEAT_DETERM_N nh (assume_tac i)
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    (* The result of the quantifier elimination *)
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    val (th, tac) = case (prop_of pre_thm) of
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        Const ("==>", _) $ (Const (@{const_name Trueprop}, _) $ t1) $ _ =>
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    let val pth = linzqe_oracle (cterm_of thy (Envir.eta_long [] t1))
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    in
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          ((pth RS iffD2) RS pre_thm,
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            assm_tac (i + 1) THEN (if q then I else TRY) (rtac TrueI i))
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    end
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      | _ => (pre_thm, assm_tac i)
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  in rtac (((mp_step nh) o (spec_step np)) th) i THEN tac end);
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end