src/HOL/Decision_Procs/cooper_tac.ML
author huffman
Sun Mar 25 20:15:39 2012 +0200 (2012-03-25)
changeset 47108 2a1953f0d20d
parent 45654 cf10bde35973
child 47142 d64fa2ca54b8
permissions -rw-r--r--
merged fork with new numeral representation (see NEWS)
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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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  val setup: theory -> theory
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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};
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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 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 = HOL_basic_ss
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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}, @{thm "zmod_self"},
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          @{thm mod_by_0}, @{thm div_by_0},
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          @{thm "zdiv_zero"}, @{thm "zmod_zero"}, @{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 = HOL_basic_ss
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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 = HOL_basic_ss
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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 = HOL_basic_ss
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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 = HOL_basic_ss |> 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 cooper_ss 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 (Pattern.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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val setup =
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  Method.setup @{binding cooper}
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    let
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      val parse_flag = Args.$$$ "no_quantify" >> K (K false)
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    in
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      Scan.lift (Scan.optional (Args.$$$ "(" |-- Scan.repeat1 parse_flag --| Args.$$$ ")") [] >>
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        curry (Library.foldl op |>) true) >>
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      (fn q => fn ctxt => SIMPLE_METHOD' (linz_tac ctxt q))
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    end
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    "decision procedure for linear integer arithmetic";
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end