src/Tools/IsaPlanner/isand.ML
 author wenzelm Tue Jun 02 09:16:19 2015 +0200 (2015-06-02) changeset 60358 aebfbcab1eb8 parent 59641 a2d056424d3c permissions -rw-r--r--
clarified context;
```     1 (*  Title:      Tools/IsaPlanner/isand.ML
```
```     2     Author:     Lucas Dixon, University of Edinburgh
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```     3
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```     4 Natural Deduction tools (obsolete).
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```     5
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```     6 For working with Isabelle theorems in a natural detuction style.
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```     7 ie, not having to deal with meta level quantified varaibles,
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```     8 instead, we work with newly introduced frees, and hide the
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```     9 "all"'s, exporting results from theorems proved with the frees, to
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```    10 solve the all cases of the previous goal. This allows resolution
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```    11 to do proof search normally.
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```    12
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```    13 Note: A nice idea: allow exporting to solve any subgoal, thus
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```    14 allowing the interleaving of proof, or provide a structure for the
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```    15 ordering of proof, thus allowing proof attempts in parrell, but
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```    16 recording the order to apply things in.
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```    17
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```    18 THINK: are we really ok with our varify name w.r.t the prop - do
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```    19 we also need to avoid names in the hidden hyps? What about
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```    20 unification contraints in flex-flex pairs - might they also have
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```    21 extra free vars?
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```    22 *)
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```    23
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```    24 signature ISA_ND =
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```    25 sig
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```    26   val variant_names: Proof.context -> term list -> string list -> string list
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```    27
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```    28   (* meta level fixed params (i.e. !! vars) *)
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```    29   val fix_alls_term: Proof.context -> int -> term -> term * term list
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```    30
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```    31   (* assumptions/subgoals *)
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```    32   val fixed_subgoal_thms: Proof.context -> thm -> thm list * (thm list -> thm)
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```    33 end
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```    34
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```    35 structure IsaND : ISA_ND =
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```    36 struct
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```    37
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```    38 (* datatype to capture an exported result, ie a fix or assume. *)
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```    39 datatype export =
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```    40   Export of
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```    41    {fixes : Thm.cterm list, (* fixed vars *)
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```    42     assumes : Thm.cterm list, (* hidden hyps/assumed prems *)
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```    43     sgid : int,
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```    44     gth :  Thm.thm}; (* subgoal/goalthm *)
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```    45
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```    46 (* exporting function that takes a solution to the fixed/assumed goal,
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```    47 and uses this to solve the subgoal in the main theorem *)
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```    48 fun export_solution (Export {fixes = cfvs, assumes = hcprems, sgid = i, gth = gth}) solth =
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```    49   let
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```    50     val solth' = solth
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```    51       |> Drule.implies_intr_list hcprems
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```    52       |> Drule.forall_intr_list cfvs;
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```    53   in Drule.compose (solth', i, gth) end;
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```    54
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```    55 fun variant_names ctxt ts xs =
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```    56   let
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```    57     val names =
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```    58       Variable.names_of ctxt
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```    59       |> (fold o fold_aterms)
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```    60           (fn Var ((a, _), _) => Name.declare a
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```    61             | Free (a, _) => Name.declare a
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```    62             | _ => I) ts;
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```    63   in fst (fold_map Name.variant xs names) end;
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```    64
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```    65 (* fix parameters of a subgoal "i", as free variables, and create an
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```    66 exporting function that will use the result of this proved goal to
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```    67 show the goal in the original theorem.
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```    68
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```    69 Note, an advantage of this over Isar is that it supports instantiation
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```    70 of unkowns in the earlier theorem, ie we can do instantiation of meta
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```    71 vars!
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```    72
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```    73 avoids constant, free and vars names.
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```    74
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```    75 loosely corresponds to:
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```    76 Given "[| SG0; ... !! x. As ==> SGi x; ... SGm |] ==> G" : thm
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```    77 Result:
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```    78   ("(As ==> SGi x') ==> (As ==> SGi x')" : thm,
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```    79    expf :
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```    80      ("As ==> SGi x'" : thm) ->
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```    81      ("[| SG0; ... SGi-1; SGi+1; ... SGm |] ==> G") : thm)
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```    82 *)
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```    83 fun fix_alls_term ctxt i t =
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```    84   let
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```    85     val gt = Logic.get_goal t i;
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```    86     val body = Term.strip_all_body gt;
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```    87     val alls = rev (Term.strip_all_vars gt);
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```    88     val xs = variant_names ctxt [t] (map fst alls);
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```    89     val fvs = map Free (xs ~~ map snd alls);
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```    90   in ((subst_bounds (fvs,body)), fvs) end;
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```    91
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```    92 fun fix_alls_cterm ctxt i th =
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```    93   let
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```    94     val (fixedbody, fvs) = fix_alls_term ctxt i (Thm.prop_of th);
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```    95     val cfvs = rev (map (Thm.cterm_of ctxt) fvs);
```
```    96     val ct_body = Thm.cterm_of ctxt fixedbody;
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```    97   in (ct_body, cfvs) end;
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```    98
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```    99 fun fix_alls' ctxt i = apfst Thm.trivial o fix_alls_cterm ctxt i;
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```   100
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```   101
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```   102 (* hide other goals *)
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```   103 (* note the export goal is rotated by (i - 1) and will have to be
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```   104 unrotated to get backto the originial position(s) *)
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```   105 fun hide_other_goals th =
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```   106   let
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```   107     (* tl beacuse fst sg is the goal we are interested in *)
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```   108     val cprems = tl (Drule.cprems_of th);
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```   109     val aprems = map Thm.assume cprems;
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```   110   in (Drule.implies_elim_list (Drule.rotate_prems 1 th) aprems, cprems) end;
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```   111
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```   112 (* a nicer version of the above that leaves only a single subgoal (the
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```   113 other subgoals are hidden hyps, that the exporter suffles about)
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```   114 namely the subgoal that we were trying to solve. *)
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```   115 (* loosely corresponds to:
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```   116 Given "[| SG0; ... !! x. As ==> SGi x; ... SGm |] ==> G" : thm
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```   117 Result:
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```   118   ("(As ==> SGi x') ==> SGi x'" : thm,
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```   119    expf :
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```   120      ("SGi x'" : thm) ->
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```   121      ("[| SG0; ... SGi-1; SGi+1; ... SGm |] ==> G") : thm)
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```   122 *)
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```   123 fun fix_alls ctxt i th =
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```   124   let
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```   125     val (fixed_gth, fixedvars) = fix_alls' ctxt i th
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```   126     val (sml_gth, othergoals) = hide_other_goals fixed_gth
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```   127   in (sml_gth, Export {fixes = fixedvars, assumes = othergoals, sgid = i, gth = th}) end;
```
```   128
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```   129
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```   130 (* Fixme: allow different order of subgoals given to expf *)
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```   131 (* make each subgoal into a separate thm that needs to be proved *)
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```   132 (* loosely corresponds to:
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```   133 Given
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```   134   "[| SG0; ... SGm |] ==> G" : thm
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```   135 Result:
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```   136 (["SG0 ==> SG0", ... ,"SGm ==> SGm"] : thm list, -- goals
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```   137  ["SG0", ..., "SGm"] : thm list ->   -- export function
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```   138    "G" : thm)
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```   139 *)
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```   140 fun subgoal_thms ctxt th =
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```   141   let
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```   142     val t = Thm.prop_of th;
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```   143
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```   144     val prems = Logic.strip_imp_prems t;
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```   145     val aprems = map (Thm.trivial o Thm.cterm_of ctxt) prems;
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```   146
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```   147     fun explortf premths = Drule.implies_elim_list th premths;
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```   148   in (aprems, explortf) end;
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```   149
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```   150
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```   151 (* Fixme: allow different order of subgoals in exportf *)
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```   152 (* as above, but also fix all parameters in all subgoals, and uses
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```   153 fix_alls, not fix_alls', ie doesn't leave extra asumptions as apparent
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```   154 subgoals. *)
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```   155 (* loosely corresponds to:
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```   156 Given
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```   157   "[| !! x0s. A0s x0s ==> SG0 x0s;
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```   158       ...; !! xms. Ams xms ==> SGm xms|] ==> G" : thm
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```   159 Result:
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```   160 (["(A0s x0s' ==> SG0 x0s') ==> SG0 x0s'",
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```   161   ... ,"(Ams xms' ==> SGm xms') ==> SGm xms'"] : thm list, -- goals
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```   162  ["SG0 x0s'", ..., "SGm xms'"] : thm list ->   -- export function
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```   163    "G" : thm)
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```   164 *)
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```   165 (* requires being given solutions! *)
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```   166 fun fixed_subgoal_thms ctxt th =
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```   167   let
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```   168     val (subgoals, expf) = subgoal_thms ctxt th;
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```   169 (*  fun export_sg (th, exp) = exp th; *)
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```   170     fun export_sgs expfs solthms =
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```   171       expf (map2 (curry (op |>)) solthms expfs);
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```   172 (*    expf (map export_sg (ths ~~ expfs)); *)
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```   173   in
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```   174     apsnd export_sgs
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```   175       (Library.split_list (map (apsnd export_solution o fix_alls ctxt 1) subgoals))
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```   176   end;
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```   177
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```   178 end;
```