1 (* Title: HOL/Tools/Sledgehammer/sledgehammer_mepo.ML
2 Author: Jia Meng, Cambridge University Computer Laboratory and NICTA
3 Author: Jasmin Blanchette, TU Muenchen
5 Sledgehammer's iterative relevance filter (MePo = Meng-Paulson).
8 signature SLEDGEHAMMER_MEPO =
10 type stature = ATP_Problem_Generate.stature
11 type fact = Sledgehammer_Fact.fact
12 type params = Sledgehammer_Provers.params
13 type relevance_fudge = Sledgehammer_Provers.relevance_fudge
15 val trace : bool Config.T
16 val pseudo_abs_name : string
17 val pseudo_skolem_prefix : string
18 val const_names_in_fact :
19 theory -> (string * typ -> term list -> bool * term list) -> term
21 val iterative_relevant_facts :
22 Proof.context -> params -> string -> int -> relevance_fudge option
23 -> term list -> term -> fact list -> fact list
26 structure Sledgehammer_MePo : SLEDGEHAMMER_MEPO =
29 open ATP_Problem_Generate
30 open Sledgehammer_Fact
31 open Sledgehammer_Provers
34 Attrib.setup_config_bool @{binding sledgehammer_filter_iter_trace} (K false)
35 fun trace_msg ctxt msg = if Config.get ctxt trace then tracing (msg ()) else ()
37 val sledgehammer_prefix = "Sledgehammer" ^ Long_Name.separator
38 val pseudo_abs_name = sledgehammer_prefix ^ "abs"
39 val pseudo_skolem_prefix = sledgehammer_prefix ^ "sko"
40 val theory_const_suffix = Long_Name.separator ^ " 1"
42 fun order_of_type (Type (@{type_name fun}, [T1, T2])) =
43 Int.max (order_of_type T1 + 1, order_of_type T2)
44 | order_of_type (Type (_, Ts)) = fold (Integer.max o order_of_type) Ts 0
47 (* An abstraction of Isabelle types and first-order terms *)
48 datatype pattern = PVar | PApp of string * pattern list
49 datatype ptype = PType of int * pattern list
51 fun string_for_pattern PVar = "_"
52 | string_for_pattern (PApp (s, ps)) =
53 if null ps then s else s ^ string_for_patterns ps
54 and string_for_patterns ps = "(" ^ commas (map string_for_pattern ps) ^ ")"
55 fun string_for_ptype (PType (_, ps)) = string_for_patterns ps
57 (*Is the second type an instance of the first one?*)
58 fun match_pattern (PVar, _) = true
59 | match_pattern (PApp _, PVar) = false
60 | match_pattern (PApp (s, ps), PApp (t, qs)) =
61 s = t andalso match_patterns (ps, qs)
62 and match_patterns (_, []) = true
63 | match_patterns ([], _) = false
64 | match_patterns (p :: ps, q :: qs) =
65 match_pattern (p, q) andalso match_patterns (ps, qs)
66 fun match_ptype (PType (_, ps), PType (_, qs)) = match_patterns (ps, qs)
68 (* Is there a unifiable constant? *)
69 fun pconst_mem f consts (s, ps) =
70 exists (curry (match_ptype o f) ps)
71 (map snd (filter (curry (op =) s o fst) consts))
72 fun pconst_hyper_mem f const_tab (s, ps) =
73 exists (curry (match_ptype o f) ps) (these (Symtab.lookup const_tab s))
75 fun pattern_for_type (Type (s, Ts)) = PApp (s, map pattern_for_type Ts)
76 | pattern_for_type (TFree (s, _)) = PApp (s, [])
77 | pattern_for_type (TVar _) = PVar
79 (* Pairs a constant with the list of its type instantiations. *)
80 fun ptype thy const x =
81 (if const then map pattern_for_type (these (try (Sign.const_typargs thy) x))
83 fun rich_ptype thy const (s, T) =
84 PType (order_of_type T, ptype thy const (s, T))
85 fun rich_pconst thy const (s, T) = (s, rich_ptype thy const (s, T))
87 fun string_for_hyper_pconst (s, ps) =
88 s ^ "{" ^ commas (map string_for_ptype ps) ^ "}"
90 (* Add a pconstant to the table, but a [] entry means a standard
91 connective, which we ignore.*)
92 fun add_pconst_to_table also_skolem (s, p) =
93 if (not also_skolem andalso String.isPrefix pseudo_skolem_prefix s) then I
94 else Symtab.map_default (s, [p]) (insert (op =) p)
96 (* Set constants tend to pull in too many irrelevant facts. We limit the damage
97 by treating them more or less as if they were built-in but add their
98 axiomatization at the end. *)
99 val set_consts = [@{const_name Collect}, @{const_name Set.member}]
100 val set_thms = @{thms Collect_mem_eq mem_Collect_eq Collect_cong}
102 fun add_pconsts_in_term thy is_built_in_const also_skolems pos =
104 val flip = Option.map not
105 (* We include free variables, as well as constants, to handle locales. For
106 each quantifiers that must necessarily be skolemized by the automatic
107 prover, we introduce a fresh constant to simulate the effect of
109 fun do_const const ext_arg (x as (s, _)) ts =
110 let val (built_in, ts) = is_built_in_const x ts in
111 if member (op =) set_consts s then
112 fold (do_term ext_arg) ts
115 ? add_pconst_to_table also_skolems (rich_pconst thy const x))
116 #> fold (do_term false) ts
118 and do_term ext_arg t =
120 (Const x, ts) => do_const true ext_arg x ts
121 | (Free x, ts) => do_const false ext_arg x ts
122 | (Abs (_, T, t'), ts) =>
123 ((null ts andalso not ext_arg)
124 (* Since lambdas on the right-hand side of equalities are usually
125 extensionalized later by "abs_extensionalize_term", we don't
126 penalize them here. *)
127 ? add_pconst_to_table true (pseudo_abs_name,
128 PType (order_of_type T + 1, [])))
129 #> fold (do_term false) (t' :: ts)
130 | (_, ts) => fold (do_term false) ts
131 fun do_quantifier will_surely_be_skolemized abs_T body_t =
132 do_formula pos body_t
133 #> (if also_skolems andalso will_surely_be_skolemized then
134 add_pconst_to_table true (pseudo_skolem_prefix ^ serial_string (),
135 PType (order_of_type abs_T, []))
138 and do_term_or_formula ext_arg T =
139 if T = HOLogic.boolT then do_formula NONE else do_term ext_arg
140 and do_formula pos t =
142 Const (@{const_name all}, _) $ Abs (_, T, t') =>
143 do_quantifier (pos = SOME false) T t'
144 | @{const "==>"} $ t1 $ t2 =>
145 do_formula (flip pos) t1 #> do_formula pos t2
146 | Const (@{const_name "=="}, Type (_, [T, _])) $ t1 $ t2 =>
147 do_term_or_formula false T t1 #> do_term_or_formula true T t2
148 | @{const Trueprop} $ t1 => do_formula pos t1
149 | @{const False} => I
151 | @{const Not} $ t1 => do_formula (flip pos) t1
152 | Const (@{const_name All}, _) $ Abs (_, T, t') =>
153 do_quantifier (pos = SOME false) T t'
154 | Const (@{const_name Ex}, _) $ Abs (_, T, t') =>
155 do_quantifier (pos = SOME true) T t'
156 | @{const HOL.conj} $ t1 $ t2 => fold (do_formula pos) [t1, t2]
157 | @{const HOL.disj} $ t1 $ t2 => fold (do_formula pos) [t1, t2]
158 | @{const HOL.implies} $ t1 $ t2 =>
159 do_formula (flip pos) t1 #> do_formula pos t2
160 | Const (@{const_name HOL.eq}, Type (_, [T, _])) $ t1 $ t2 =>
161 do_term_or_formula false T t1 #> do_term_or_formula true T t2
162 | Const (@{const_name If}, Type (_, [_, Type (_, [T, _])]))
164 do_formula NONE t1 #> fold (do_term_or_formula false T) [t2, t3]
165 | Const (@{const_name Ex1}, _) $ Abs (_, T, t') =>
166 do_quantifier (is_some pos) T t'
167 | Const (@{const_name Ball}, _) $ t1 $ Abs (_, T, t') =>
168 do_quantifier (pos = SOME false) T
169 (HOLogic.mk_imp (incr_boundvars 1 t1 $ Bound 0, t'))
170 | Const (@{const_name Bex}, _) $ t1 $ Abs (_, T, t') =>
171 do_quantifier (pos = SOME true) T
172 (HOLogic.mk_conj (incr_boundvars 1 t1 $ Bound 0, t'))
173 | (t0 as Const (_, @{typ bool})) $ t1 =>
174 do_term false t0 #> do_formula pos t1 (* theory constant *)
175 | _ => do_term false t
176 in do_formula pos end
178 fun pconsts_in_fact thy is_built_in_const t =
179 Symtab.fold (fn (s, pss) => fold (cons o pair s) pss)
180 (Symtab.empty |> add_pconsts_in_term thy is_built_in_const true
183 val const_names_in_fact = map fst ooo pconsts_in_fact
185 (* Inserts a dummy "constant" referring to the theory name, so that relevance
186 takes the given theory into account. *)
187 fun theory_constify ({theory_const_rel_weight, theory_const_irrel_weight, ...}
188 : relevance_fudge) thy_name t =
189 if exists (curry (op <) 0.0) [theory_const_rel_weight,
190 theory_const_irrel_weight] then
191 Const (thy_name ^ theory_const_suffix, @{typ bool}) $ t
195 fun theory_const_prop_of fudge th =
196 theory_constify fudge (Context.theory_name (theory_of_thm th)) (prop_of th)
198 fun pair_consts_fact thy is_built_in_const fudge fact =
199 case fact |> snd |> theory_const_prop_of fudge
200 |> pconsts_in_fact thy is_built_in_const of
202 | consts => SOME ((fact, consts), NONE)
204 (* A two-dimensional symbol table counts frequencies of constants. It's keyed
205 first by constant name and second by its list of type instantiations. For the
206 latter, we need a linear ordering on "pattern list". *)
210 (PVar, PVar) => EQUAL
211 | (PVar, PApp _) => LESS
212 | (PApp _, PVar) => GREATER
213 | (PApp q1, PApp q2) =>
214 prod_ord fast_string_ord (dict_ord pattern_ord) (q1, q2)
215 fun ptype_ord (PType p, PType q) =
216 prod_ord (dict_ord pattern_ord) int_ord (swap p, swap q)
218 structure PType_Tab = Table(type key = ptype val ord = ptype_ord)
220 fun count_fact_consts thy fudge =
222 fun do_const const (s, T) ts =
223 (* Two-dimensional table update. Constant maps to types maps to count. *)
224 PType_Tab.map_default (rich_ptype thy const (s, T), 0) (Integer.add 1)
225 |> Symtab.map_default (s, PType_Tab.empty)
229 (Const x, ts) => do_const true x ts
230 | (Free x, ts) => do_const false x ts
231 | (Abs (_, _, t'), ts) => fold do_term (t' :: ts)
232 | (_, ts) => fold do_term ts
233 in do_term o theory_const_prop_of fudge o snd end
235 fun pow_int _ 0 = 1.0
237 | pow_int x n = if n > 0 then x * pow_int x (n - 1) else pow_int x (n + 1) / x
239 (*The frequency of a constant is the sum of those of all instances of its type.*)
240 fun pconst_freq match const_tab (c, ps) =
241 PType_Tab.fold (fn (qs, m) => match (ps, qs) ? Integer.add m)
242 (the (Symtab.lookup const_tab c)) 0
245 (* A surprising number of theorems contain only a few significant constants.
246 These include all induction rules, and other general theorems. *)
248 (* "log" seems best in practice. A constant function of one ignores the constant
249 frequencies. Rare constants give more points if they are relevant than less
251 fun rel_weight_for _ freq = 1.0 + 2.0 / Math.ln (Real.fromInt freq + 1.0)
253 (* Irrelevant constants are treated differently. We associate lower penalties to
254 very rare constants and very common ones -- the former because they can't
255 lead to the inclusion of too many new facts, and the latter because they are
256 so common as to be of little interest. *)
257 fun irrel_weight_for ({worse_irrel_freq, higher_order_irrel_weight, ...}
258 : relevance_fudge) order freq =
259 let val (k, x) = worse_irrel_freq |> `Real.ceil in
260 (if freq < k then Math.ln (Real.fromInt (freq + 1)) / Math.ln x
261 else rel_weight_for order freq / rel_weight_for order k)
262 * pow_int higher_order_irrel_weight (order - 1)
265 fun multiplier_for_const_name local_const_multiplier s =
266 if String.isSubstring "." s then 1.0 else local_const_multiplier
268 (* Computes a constant's weight, as determined by its frequency. *)
269 fun generic_pconst_weight local_const_multiplier abs_weight skolem_weight
270 theory_const_weight chained_const_weight weight_for f
271 const_tab chained_const_tab (c as (s, PType (m, _))) =
272 if s = pseudo_abs_name then
274 else if String.isPrefix pseudo_skolem_prefix s then
276 else if String.isSuffix theory_const_suffix s then
279 multiplier_for_const_name local_const_multiplier s
280 * weight_for m (pconst_freq (match_ptype o f) const_tab c)
281 |> (if chained_const_weight < 1.0 andalso
282 pconst_hyper_mem I chained_const_tab c then
283 curry (op *) chained_const_weight
287 fun rel_pconst_weight ({local_const_multiplier, abs_rel_weight,
288 theory_const_rel_weight, ...} : relevance_fudge)
290 generic_pconst_weight local_const_multiplier abs_rel_weight 0.0
291 theory_const_rel_weight 0.0 rel_weight_for I const_tab
294 fun irrel_pconst_weight (fudge as {local_const_multiplier, abs_irrel_weight,
296 theory_const_irrel_weight,
297 chained_const_irrel_weight, ...})
298 const_tab chained_const_tab =
299 generic_pconst_weight local_const_multiplier abs_irrel_weight
300 skolem_irrel_weight theory_const_irrel_weight
301 chained_const_irrel_weight (irrel_weight_for fudge) swap
302 const_tab chained_const_tab
304 fun stature_bonus ({intro_bonus, ...} : relevance_fudge) (_, Intro) =
306 | stature_bonus {elim_bonus, ...} (_, Elim) = elim_bonus
307 | stature_bonus {simp_bonus, ...} (_, Simp) = simp_bonus
308 | stature_bonus {local_bonus, ...} (Local, _) = local_bonus
309 | stature_bonus {assum_bonus, ...} (Assum, _) = assum_bonus
310 | stature_bonus {chained_bonus, ...} (Chained, _) = chained_bonus
311 | stature_bonus _ _ = 0.0
313 fun is_odd_const_name s =
314 s = pseudo_abs_name orelse String.isPrefix pseudo_skolem_prefix s orelse
315 String.isSuffix theory_const_suffix s
317 fun fact_weight fudge stature const_tab relevant_consts chained_consts
319 case fact_consts |> List.partition (pconst_hyper_mem I relevant_consts)
320 ||> filter_out (pconst_hyper_mem swap relevant_consts) of
323 if forall (forall (is_odd_const_name o fst)) [rel, irrel] then
327 val irrel = irrel |> filter_out (pconst_mem swap rel)
329 0.0 |> fold (curry (op +) o rel_pconst_weight fudge const_tab) rel
331 ~ (stature_bonus fudge stature)
332 |> fold (curry (op +)
333 o irrel_pconst_weight fudge const_tab chained_consts) irrel
334 val res = rel_weight / (rel_weight + irrel_weight)
335 in if Real.isFinite res then res else 0.0 end
337 fun take_most_relevant ctxt max_facts remaining_max
338 ({max_imperfect, max_imperfect_exp, ...} : relevance_fudge)
339 (candidates : ((fact * (string * ptype) list) * real) list) =
342 Real.ceil (Math.pow (max_imperfect,
343 Math.pow (Real.fromInt remaining_max
344 / Real.fromInt max_facts, max_imperfect_exp)))
345 val (perfect, imperfect) =
346 candidates |> sort (Real.compare o swap o pairself snd)
347 |> take_prefix (fn (_, w) => w > 0.99999)
348 val ((accepts, more_rejects), rejects) =
349 chop max_imperfect imperfect |>> append perfect |>> chop remaining_max
351 trace_msg ctxt (fn () =>
352 "Actually passed (" ^ string_of_int (length accepts) ^ " of " ^
353 string_of_int (length candidates) ^ "): " ^
354 (accepts |> map (fn ((((name, _), _), _), weight) =>
355 name () ^ " [" ^ Real.toString weight ^ "]")
357 (accepts, more_rejects @ rejects)
360 fun if_empty_replace_with_scope thy is_built_in_const facts sc tab =
361 if Symtab.is_empty tab then
363 |> fold (add_pconsts_in_term thy is_built_in_const false (SOME false))
364 (map_filter (fn ((_, (sc', _)), th) =>
365 if sc' = sc then SOME (prop_of th) else NONE) facts)
369 fun consider_arities is_built_in_const th =
371 fun aux _ _ NONE = NONE
372 | aux t args (SOME tab) =
374 t1 $ t2 => SOME tab |> aux t1 (t2 :: args) |> aux t2 []
375 | Const (x as (s, _)) =>
376 (if is_built_in_const x args |> fst then
378 else case Symtab.lookup tab s of
379 NONE => SOME (Symtab.update (s, length args) tab)
380 | SOME n => if n = length args then SOME tab else NONE)
382 in aux (prop_of th) [] end
384 (* FIXME: This is currently only useful for polymorphic type encodings. *)
385 fun could_benefit_from_ext is_built_in_const facts =
386 fold (consider_arities is_built_in_const o snd) facts (SOME Symtab.empty)
389 (* High enough so that it isn't wrongly considered as very relevant (e.g., for E
390 weights), but low enough so that it is unlikely to be truncated away if few
391 facts are included. *)
392 val special_fact_index = 75
394 fun relevance_filter ctxt thres0 decay max_facts is_built_in_const
395 (fudge as {threshold_divisor, ridiculous_threshold, ...}) facts hyp_ts
398 val thy = Proof_Context.theory_of ctxt
399 val const_tab = fold (count_fact_consts thy fudge) facts Symtab.empty
400 val add_pconsts = add_pconsts_in_term thy is_built_in_const false o SOME
402 facts |> map_filter (fn ((_, (Chained, _)), th) => SOME (prop_of th)
404 val chained_const_tab = Symtab.empty |> fold (add_pconsts true) chained_ts
406 Symtab.empty |> fold (add_pconsts true) hyp_ts
407 |> add_pconsts false concl_t
408 |> (fn tab => if Symtab.is_empty tab then chained_const_tab else tab)
409 |> fold (if_empty_replace_with_scope thy is_built_in_const facts)
410 [Chained, Assum, Local]
411 fun iter j remaining_max thres rel_const_tab hopeless hopeful =
413 fun relevant [] _ [] =
414 (* Nothing has been added this iteration. *)
415 if j = 0 andalso thres >= ridiculous_threshold then
416 (* First iteration? Try again. *)
417 iter 0 max_facts (thres / threshold_divisor) rel_const_tab
421 | relevant candidates rejects [] =
423 val (accepts, more_rejects) =
424 take_most_relevant ctxt max_facts remaining_max fudge candidates
427 |> fold (add_pconst_to_table false) (maps (snd o fst) accepts)
428 fun is_dirty (c, _) =
429 Symtab.lookup rel_const_tab' c <> Symtab.lookup rel_const_tab c
430 val (hopeful_rejects, hopeless_rejects) =
431 (rejects @ hopeless, ([], []))
432 |-> fold (fn (ax as (_, consts), old_weight) =>
433 if exists is_dirty consts then
434 apfst (cons (ax, NONE))
436 apsnd (cons (ax, old_weight)))
437 |>> append (more_rejects
438 |> map (fn (ax as (_, consts), old_weight) =>
439 (ax, if exists is_dirty consts then NONE
440 else SOME old_weight)))
443 * Math.pow (decay, Real.fromInt (length accepts))
444 val remaining_max = remaining_max - length accepts
446 trace_msg ctxt (fn () => "New or updated constants: " ^
447 commas (rel_const_tab' |> Symtab.dest
448 |> subtract (op =) (rel_const_tab |> Symtab.dest)
449 |> map string_for_hyper_pconst));
450 map (fst o fst) accepts @
451 (if remaining_max = 0 then
454 iter (j + 1) remaining_max thres rel_const_tab'
455 hopeless_rejects hopeful_rejects)
457 | relevant candidates rejects
458 (((ax as (((_, stature), _), fact_consts)), cached_weight)
462 case cached_weight of
464 | NONE => fact_weight fudge stature const_tab rel_const_tab
465 chained_const_tab fact_consts
467 if weight >= thres then
468 relevant ((ax, weight) :: candidates) rejects hopeful
470 relevant candidates ((ax, weight) :: rejects) hopeful
473 trace_msg ctxt (fn () =>
474 "ITERATION " ^ string_of_int j ^ ": current threshold: " ^
475 Real.toString thres ^ ", constants: " ^
476 commas (rel_const_tab |> Symtab.dest
477 |> filter (curry (op <>) [] o snd)
478 |> map string_for_hyper_pconst));
479 relevant [] [] hopeful
482 fold_aterms (curry (fn (Const (s', _), false) => s' = s | (_, b) => b)) t
484 fun uses_const_anywhere accepts s =
485 exists (uses_const s o prop_of o snd) accepts orelse
486 exists (uses_const s) (concl_t :: hyp_ts)
487 fun add_set_const_thms accepts =
488 exists (uses_const_anywhere accepts) set_consts ? append set_thms
489 fun insert_into_facts accepts [] = accepts
490 | insert_into_facts accepts ths =
492 val add = facts |> filter (member Thm.eq_thm_prop ths o snd)
494 accepts |> filter_out (member Thm.eq_thm_prop ths o snd)
495 |> take (max_facts - length add)
496 |> chop special_fact_index
497 in bef @ add @ after end
498 fun insert_special_facts accepts =
499 (* FIXME: get rid of "ext" here once it is treated as a helper *)
500 [] |> could_benefit_from_ext is_built_in_const accepts ? cons @{thm ext}
501 |> add_set_const_thms accepts
502 |> insert_into_facts accepts
504 facts |> map_filter (pair_consts_fact thy is_built_in_const fudge)
505 |> iter 0 max_facts thres0 goal_const_tab []
506 |> insert_special_facts
507 |> tap (fn accepts => trace_msg ctxt (fn () =>
508 "Total relevant: " ^ string_of_int (length accepts)))
511 fun iterative_relevant_facts ctxt
512 ({fact_thresholds = (thres0, thres1), ...} : params) prover
513 max_facts fudge hyp_ts concl_t facts =
515 val thy = Proof_Context.theory_of ctxt
516 val is_built_in_const =
517 Sledgehammer_Provers.is_built_in_const_for_prover ctxt prover
521 | NONE => Sledgehammer_Provers.relevance_fudge_for_prover ctxt prover
522 val decay = Math.pow ((1.0 - thres1) / (1.0 - thres0),
523 1.0 / Real.fromInt (max_facts + 1))
525 trace_msg ctxt (fn () => "Considering " ^ string_of_int (length facts) ^
527 (if thres1 < 0.0 then
529 else if thres0 > 1.0 orelse thres0 > thres1 then
532 relevance_filter ctxt thres0 decay max_facts is_built_in_const fudge
534 (concl_t |> theory_constify fudge (Context.theory_name thy)))