161 lines
5.2 KiB
Standard ML
161 lines
5.2 KiB
Standard ML
(*
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* Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*)
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(* Title: Tactics for abstract separation algebras
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Authors: Gerwin Klein and Rafal Kolanski, 2012
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Maintainers: Gerwin Klein <kleing at cse.unsw.edu.au>
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Rafal Kolanski <rafal.kolanski at nicta.com.au>
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*)
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(* Separating Conjunction (and Top, AKA sep_true) {{{
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This defines the constants and theorems necessary for the conjunct
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selection and cancelling tactic, as well as utility functions.
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*)
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structure SepConj =
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struct
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val sep_conj_term = @{term sep_conj}
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val sep_conj_str = "**"
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val sep_conj_ac = @{thms sep_conj_ac}
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val sep_conj_impl = @{thm sep_conj_impl}
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fun is_sep_conj_const (Const (@{const_name sep_conj}, _)) = true
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| is_sep_conj_const _ = false
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fun is_sep_conj_term (Const t $ _ $ _ $ _) = is_sep_conj_const (Const t)
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| is_sep_conj_term _ = false
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fun is_sep_conj_prop (Const _ $ t) = is_sep_conj_term t
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| is_sep_conj_prop _ = false
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fun strip_sep_conj (Const (@{const_name sep_conj},_) $ t1 $ t2 $ _) =
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[t1] @ (strip_sep_conj t2)
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| strip_sep_conj (Const (@{const_name sep_conj},_) $ t1 $ t2) =
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[t1] @ (strip_sep_conj t2)
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(* dig through eta exanded terms: *)
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| strip_sep_conj (Abs (_, _, t $ Bound 0)) = strip_sep_conj t
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| strip_sep_conj t = [t]
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fun is_sep_true_term (Abs (_, _, Const (@{const_name True}, _))) = true
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| is_sep_true_term _ = false
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fun mk_sep_conj (t1, t2) = sep_conj_term $ t1 $ t2
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(* Types of conjuncts and name of state type, for term construction *)
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val sep_conj_cjt_typ = type_of sep_conj_term |> domain_type
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val sep_conj_state_typn = domain_type sep_conj_cjt_typ |> dest_TFree |> #1
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end
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(* }}} *)
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(* Function application terms {{{ *)
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(* Dealing with function applications of the type
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Const/Free(name,type) $ arg1 $ arg2 $ ... $ last_arg *)
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structure FunApp =
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struct
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(* apply a function term to a Free with given name *)
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fun fun_app_free t free_name = t $ Free (free_name, type_of t |> domain_type)
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end (* }}} *)
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(* Selecting Conjuncts in Premise or Conclusion {{{ *)
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(* Constructs a rearrangement lemma of the kind:
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(A ** B ** C) s ==> (C ** A ** B) s
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When cjt_select = 2 (0-based index of C) and
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cjt_select = 3 (number of conjuncts to use), conclusion = true
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"conclusion" specifies whether the rearrangement occurs in conclusion
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(for dtac) or the premise (for rtac) of the rule.
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*)
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fun mk_sep_select_rule ctxt conclusion (cjt_count, cjt_selects) =
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let
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fun variants nctxt names = fold_map Name.variant names nctxt
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val (state, nctxt0) = Name.variant "s" (Variable.names_of ctxt)
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fun mk_cjt n = Free (n, type_of SepConj.sep_conj_term |> domain_type)
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fun sep_conj_prop cjts =
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FunApp.fun_app_free (foldr1 SepConj.mk_sep_conj (map mk_cjt cjts)) state |> HOLogic.mk_Trueprop
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(* concatenate string and string of an int *)
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fun conc_str_int str int = str ^ Int.toString int
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(* make the conjunct names *)
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val (cjts, _) = 1 upto cjt_count |> map (conc_str_int "a") |> variants nctxt0
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(* make normal-order separation conjunction terms *)
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val orig = sep_conj_prop cjts
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(* make reordered separation conjunction terms *)
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(* We gather the needed conjuncts, and then append it the original list with those conjuncts removed *)
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fun dropit n (x::xs) is = if exists (fn y => y = n) is then dropit (n+1) xs is else x :: dropit (n+1) xs is
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| dropit _ [] _ = []
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fun nths_to_front idxs xs = map (nth xs) idxs @ dropit 0 xs idxs
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val reordered = sep_conj_prop (nths_to_front cjt_selects cjts)
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val goal = Logic.mk_implies (if conclusion then (orig, reordered) else (reordered, orig))
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(* simp add: sep_conj_ac *)
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val sep_conj_ac_tac = Simplifier.asm_full_simp_tac
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(put_simpset HOL_basic_ss ctxt addsimps SepConj.sep_conj_ac)
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in
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Goal.prove ctxt [] [] goal (fn _ => sep_conj_ac_tac 1)
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|> Drule.generalize (Names.make_set [SepConj.sep_conj_state_typn], Names.make_set (state :: cjts))
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end
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fun conj_length ctxt ct =
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let
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val ((_, ct'), _) = Variable.focus_cterm NONE ct ctxt
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val concl = ct' |> Drule.strip_imp_concl |> Thm.term_of
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in
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concl |> HOLogic.dest_Trueprop |> SepConj.strip_sep_conj |> length
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end
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local
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fun all_uniq xs = forall (fn x => length (filter (fn y => x = y) xs) = 1 ) xs
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in
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fun sep_selects_tac ctxt ns =
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let
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fun sep_select_tac' ctxt ns (ct, i) =
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let
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fun th ns = mk_sep_select_rule ctxt false ((conj_length ctxt ct),ns)
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in
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if not (all_uniq ns)
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then error ("Duplicate numbers in arguments")
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else resolve0_tac [th ns] i handle Subscript => no_tac
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end
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in
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CSUBGOAL (sep_select_tac' ctxt (map (fn m => m - 1) ns))
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end
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end
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fun UNSOLVED' tac i st =
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tac i st |> Seq.filter (fn st' => Thm.nprems_of st' = Thm.nprems_of st)
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fun sep_flatten ctxt =
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let
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fun simptac i =
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CHANGED_PROP (full_simp_tac (put_simpset HOL_basic_ss ctxt addsimps [@{thm sep_conj_assoc}]) i)
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in
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UNSOLVED' simptac
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end
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fun sep_select_tactic lens_tac ns ctxt =
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let
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val sep_select = sep_selects_tac ctxt
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val iffI = @{thm iffI}
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val sep_conj_ac_tac =
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Simplifier.asm_full_simp_tac (put_simpset HOL_basic_ss ctxt addsimps SepConj.sep_conj_ac)
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in
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lens_tac THEN'
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resolve0_tac [iffI] THEN'
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sep_select ns THEN'
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assume_tac ctxt THEN'
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sep_conj_ac_tac
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end
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