(* Title: HOL/Tools/SMT/smt_normalize.ML
Author: Sascha Boehme, TU Muenchen
Normalization steps on theorems required by SMT solvers.
*)
signature SMT_NORMALIZE =
sig
val drop_fact_warning: Proof.context -> thm -> unit
val atomize_conv: Proof.context -> conv
type extra_norm = Proof.context -> thm list * thm list -> thm list * thm list
val add_extra_norm: SMT_Utils.class * extra_norm -> Context.generic ->
Context.generic
val normalize: (int * (int option * thm)) list -> Proof.context ->
(int * thm) list * Proof.context
val setup: theory -> theory
end
structure SMT_Normalize: SMT_NORMALIZE =
struct
fun drop_fact_warning ctxt =
SMT_Config.verbose_msg ctxt (prefix "Warning: dropping assumption: " o
Display.string_of_thm ctxt)
(* general theorem normalizations *)
(** instantiate elimination rules **)
local
val (cpfalse, cfalse) =
`SMT_Utils.mk_cprop (Thm.cterm_of @{theory} @{const False})
fun inst f ct thm =
let val cv = f (Drule.strip_imp_concl (Thm.cprop_of thm))
in Thm.instantiate ([], [(cv, ct)]) thm end
in
fun instantiate_elim thm =
(case Thm.concl_of thm of
@{const Trueprop} $ Var (_, @{typ bool}) => inst Thm.dest_arg cfalse thm
| Var _ => inst I cpfalse thm
| _ => thm)
end
(** normalize definitions **)
fun norm_def thm =
(case Thm.prop_of thm of
@{const Trueprop} $ (Const (@{const_name HOL.eq}, _) $ _ $ Abs _) =>
norm_def (thm RS @{thm fun_cong})
| Const (@{const_name Pure.eq}, _) $ _ $ Abs _ =>
norm_def (thm RS @{thm meta_eq_to_obj_eq})
| _ => thm)
(** atomization **)
fun atomize_conv ctxt ct =
(case Thm.term_of ct of
@{const Pure.imp} $ _ $ _ =>
Conv.binop_conv (atomize_conv ctxt) then_conv
Conv.rewr_conv @{thm atomize_imp}
| Const (@{const_name Pure.eq}, _) $ _ $ _ =>
Conv.binop_conv (atomize_conv ctxt) then_conv
Conv.rewr_conv @{thm atomize_eq}
| Const (@{const_name Pure.all}, _) $ Abs _ =>
Conv.binder_conv (atomize_conv o snd) ctxt then_conv
Conv.rewr_conv @{thm atomize_all}
| _ => Conv.all_conv) ct
val setup_atomize =
fold SMT_Builtin.add_builtin_fun_ext'' [@{const_name Pure.imp},
@{const_name Pure.eq}, @{const_name Pure.all}, @{const_name Trueprop}]
(** unfold special quantifiers **)
local
val ex1_def = mk_meta_eq @{lemma
"Ex1 = (%P. EX x. P x & (ALL y. P y --> y = x))"
by (rule ext) (simp only: Ex1_def)}
val ball_def = mk_meta_eq @{lemma "Ball = (%A P. ALL x. x : A --> P x)"
by (rule ext)+ (rule Ball_def)}
val bex_def = mk_meta_eq @{lemma "Bex = (%A P. EX x. x : A & P x)"
by (rule ext)+ (rule Bex_def)}
val special_quants = [(@{const_name Ex1}, ex1_def),
(@{const_name Ball}, ball_def), (@{const_name Bex}, bex_def)]
fun special_quant (Const (n, _)) = AList.lookup (op =) special_quants n
| special_quant _ = NONE
fun special_quant_conv _ ct =
(case special_quant (Thm.term_of ct) of
SOME thm => Conv.rewr_conv thm
| NONE => Conv.all_conv) ct
in
fun unfold_special_quants_conv ctxt =
SMT_Utils.if_exists_conv (is_some o special_quant)
(Conv.top_conv special_quant_conv ctxt)
val setup_unfolded_quants =
fold (SMT_Builtin.add_builtin_fun_ext'' o fst) special_quants
end
(** trigger inference **)
local
(*** check trigger syntax ***)
fun dest_trigger (Const (@{const_name pat}, _) $ _) = SOME true
| dest_trigger (Const (@{const_name nopat}, _) $ _) = SOME false
| dest_trigger _ = NONE
fun eq_list [] = false
| eq_list (b :: bs) = forall (equal b) bs
fun proper_trigger t =
t
|> these o try HOLogic.dest_list
|> map (map_filter dest_trigger o these o try HOLogic.dest_list)
|> (fn [] => false | bss => forall eq_list bss)
fun proper_quant inside f t =
(case t of
Const (@{const_name All}, _) $ Abs (_, _, u) => proper_quant true f u
| Const (@{const_name Ex}, _) $ Abs (_, _, u) => proper_quant true f u
| @{const trigger} $ p $ u =>
(if inside then f p else false) andalso proper_quant false f u
| Abs (_, _, u) => proper_quant false f u
| u1 $ u2 => proper_quant false f u1 andalso proper_quant false f u2
| _ => true)
fun check_trigger_error ctxt t =
error ("SMT triggers must only occur under quantifier and multipatterns " ^
"must have the same kind: " ^ Syntax.string_of_term ctxt t)
fun check_trigger_conv ctxt ct =
if proper_quant false proper_trigger (SMT_Utils.term_of ct) then
Conv.all_conv ct
else check_trigger_error ctxt (Thm.term_of ct)
(*** infer simple triggers ***)
fun dest_cond_eq ct =
(case Thm.term_of ct of
Const (@{const_name HOL.eq}, _) $ _ $ _ => Thm.dest_binop ct
| @{const HOL.implies} $ _ $ _ => dest_cond_eq (Thm.dest_arg ct)
| _ => raise CTERM ("no equation", [ct]))
fun get_constrs thy (Type (n, _)) = these (Datatype.get_constrs thy n)
| get_constrs _ _ = []
fun is_constr thy (n, T) =
let fun match (m, U) = m = n andalso Sign.typ_instance thy (T, U)
in can (the o find_first match o get_constrs thy o Term.body_type) T end
fun is_constr_pat thy t =
(case Term.strip_comb t of
(Free _, []) => true
| (Const c, ts) => is_constr thy c andalso forall (is_constr_pat thy) ts
| _ => false)
fun is_simp_lhs ctxt t =
(case Term.strip_comb t of
(Const c, ts as _ :: _) =>
not (SMT_Builtin.is_builtin_fun_ext ctxt c ts) andalso
forall (is_constr_pat (Proof_Context.theory_of ctxt)) ts
| _ => false)
fun has_all_vars vs t =
subset (op aconv) (vs, map Free (Term.add_frees t []))
fun minimal_pats vs ct =
if has_all_vars vs (Thm.term_of ct) then
(case Thm.term_of ct of
_ $ _ =>
(case pairself (minimal_pats vs) (Thm.dest_comb ct) of
([], []) => [[ct]]
| (ctss, ctss') => union (eq_set (op aconvc)) ctss ctss')
| _ => [])
else []
fun proper_mpat _ _ _ [] = false
| proper_mpat thy gen u cts =
let
val tps = (op ~~) (`gen (map Thm.term_of cts))
fun some_match u = tps |> exists (fn (t', t) =>
Pattern.matches thy (t', u) andalso not (t aconv u))
in not (Term.exists_subterm some_match u) end
val pat =
SMT_Utils.mk_const_pat @{theory} @{const_name SMT.pat} SMT_Utils.destT1
fun mk_pat ct = Thm.apply (SMT_Utils.instT' ct pat) ct
fun mk_clist T = pairself (Thm.cterm_of @{theory})
(HOLogic.cons_const T, HOLogic.nil_const T)
fun mk_list (ccons, cnil) f cts = fold_rev (Thm.mk_binop ccons o f) cts cnil
val mk_pat_list = mk_list (mk_clist @{typ SMT.pattern})
val mk_mpat_list = mk_list (mk_clist @{typ "SMT.pattern list"})
fun mk_trigger ctss = mk_mpat_list (mk_pat_list mk_pat) ctss
val trigger_eq =
mk_meta_eq @{lemma "p = SMT.trigger t p" by (simp add: trigger_def)}
fun insert_trigger_conv [] ct = Conv.all_conv ct
| insert_trigger_conv ctss ct =
let val (ctr, cp) = Thm.dest_binop (Thm.rhs_of trigger_eq) ||> rpair ct
in Thm.instantiate ([], [cp, (ctr, mk_trigger ctss)]) trigger_eq end
fun infer_trigger_eq_conv outer_ctxt (ctxt, cvs) ct =
let
val (lhs, rhs) = dest_cond_eq ct
val vs = map Thm.term_of cvs
val thy = Proof_Context.theory_of ctxt
fun get_mpats ct =
if is_simp_lhs ctxt (Thm.term_of ct) then minimal_pats vs ct
else []
val gen = Variable.export_terms ctxt outer_ctxt
val filter_mpats = filter (proper_mpat thy gen (Thm.term_of rhs))
in insert_trigger_conv (filter_mpats (get_mpats lhs)) ct end
fun has_trigger (@{const SMT.trigger} $ _ $ _) = true
| has_trigger _ = false
fun try_trigger_conv cv ct =
if SMT_Utils.under_quant has_trigger (SMT_Utils.term_of ct) then
Conv.all_conv ct
else Conv.try_conv cv ct
fun infer_trigger_conv ctxt =
if Config.get ctxt SMT_Config.infer_triggers then
try_trigger_conv
(SMT_Utils.under_quant_conv (infer_trigger_eq_conv ctxt) ctxt)
else Conv.all_conv
in
fun trigger_conv ctxt =
SMT_Utils.prop_conv
(check_trigger_conv ctxt then_conv infer_trigger_conv ctxt)
val setup_trigger =
fold SMT_Builtin.add_builtin_fun_ext''
[@{const_name SMT.pat}, @{const_name SMT.nopat}, @{const_name SMT.trigger}]
end
(** adding quantifier weights **)
local
(*** check weight syntax ***)
val has_no_weight =
not o Term.exists_subterm (fn @{const SMT.weight} => true | _ => false)
fun is_weight (@{const SMT.weight} $ w $ t) =
(case try HOLogic.dest_number w of
SOME (_, i) => i >= 0 andalso has_no_weight t
| _ => false)
| is_weight t = has_no_weight t
fun proper_trigger (@{const SMT.trigger} $ _ $ t) = is_weight t
| proper_trigger t = is_weight t
fun check_weight_error ctxt t =
error ("SMT weight must be a non-negative number and must only occur " ^
"under the top-most quantifier and an optional trigger: " ^
Syntax.string_of_term ctxt t)
fun check_weight_conv ctxt ct =
if SMT_Utils.under_quant proper_trigger (SMT_Utils.term_of ct) then
Conv.all_conv ct
else check_weight_error ctxt (Thm.term_of ct)
(*** insertion of weights ***)
fun under_trigger_conv cv ct =
(case Thm.term_of ct of
@{const SMT.trigger} $ _ $ _ => Conv.arg_conv cv
| _ => cv) ct
val weight_eq =
mk_meta_eq @{lemma "p = SMT.weight i p" by (simp add: weight_def)}
fun mk_weight_eq w =
let val cv = Thm.dest_arg1 (Thm.rhs_of weight_eq)
in
Thm.instantiate ([], [(cv, Numeral.mk_cnumber @{ctyp int} w)]) weight_eq
end
fun add_weight_conv NONE _ = Conv.all_conv
| add_weight_conv (SOME weight) ctxt =
let val cv = Conv.rewr_conv (mk_weight_eq weight)
in SMT_Utils.under_quant_conv (K (under_trigger_conv cv)) ctxt end
in
fun weight_conv weight ctxt =
SMT_Utils.prop_conv
(check_weight_conv ctxt then_conv add_weight_conv weight ctxt)
val setup_weight = SMT_Builtin.add_builtin_fun_ext'' @{const_name SMT.weight}
end
(** combined general normalizations **)
fun gen_normalize1_conv ctxt weight =
atomize_conv ctxt then_conv
unfold_special_quants_conv ctxt then_conv
Thm.beta_conversion true then_conv
trigger_conv ctxt then_conv
weight_conv weight ctxt
fun gen_normalize1 ctxt weight thm =
thm
|> instantiate_elim
|> norm_def
|> Conv.fconv_rule (Thm.beta_conversion true then_conv Thm.eta_conversion)
|> Drule.forall_intr_vars
|> Conv.fconv_rule (gen_normalize1_conv ctxt weight)
fun gen_norm1_safe ctxt (i, (weight, thm)) =
(case try (gen_normalize1 ctxt weight) thm of
SOME thm' => SOME (i, thm')
| NONE => (drop_fact_warning ctxt thm; NONE))
fun gen_normalize ctxt iwthms = map_filter (gen_norm1_safe ctxt) iwthms
(* unfolding of definitions and theory-specific rewritings *)
fun expand_head_conv cv ct =
(case Thm.term_of ct of
_ $ _ =>
Conv.fun_conv (expand_head_conv cv) then_conv
Conv.try_conv (Thm.beta_conversion false)
| _ => cv) ct
(** rewrite bool case expressions as if expressions **)
local
fun is_case_bool (Const (@{const_name "bool.case_bool"}, _)) = true
| is_case_bool _ = false
val thm = mk_meta_eq @{lemma
"case_bool = (%x y P. if P then x else y)" by (rule ext)+ simp}
fun unfold_conv _ =
SMT_Utils.if_true_conv (is_case_bool o Term.head_of)
(expand_head_conv (Conv.rewr_conv thm))
in
fun rewrite_case_bool_conv ctxt =
SMT_Utils.if_exists_conv is_case_bool (Conv.top_conv unfold_conv ctxt)
val setup_case_bool =
SMT_Builtin.add_builtin_fun_ext'' @{const_name "bool.case_bool"}
end
(** unfold abs, min and max **)
local
val abs_def = mk_meta_eq @{lemma
"abs = (%a::'a::abs_if. if a < 0 then - a else a)"
by (rule ext) (rule abs_if)}
val min_def = mk_meta_eq @{lemma "min = (%a b. if a <= b then a else b)"
by (rule ext)+ (rule min_def)}
val max_def = mk_meta_eq @{lemma "max = (%a b. if a <= b then b else a)"
by (rule ext)+ (rule max_def)}
val defs = [(@{const_name min}, min_def), (@{const_name max}, max_def),
(@{const_name abs}, abs_def)]
fun is_builtinT ctxt T =
SMT_Builtin.is_builtin_typ_ext ctxt (Term.domain_type T)
fun abs_min_max ctxt (Const (n, T)) =
(case AList.lookup (op =) defs n of
NONE => NONE
| SOME thm => if is_builtinT ctxt T then SOME thm else NONE)
| abs_min_max _ _ = NONE
fun unfold_amm_conv ctxt ct =
(case abs_min_max ctxt (Term.head_of (Thm.term_of ct)) of
SOME thm => expand_head_conv (Conv.rewr_conv thm)
| NONE => Conv.all_conv) ct
in
fun unfold_abs_min_max_conv ctxt =
SMT_Utils.if_exists_conv (is_some o abs_min_max ctxt)
(Conv.top_conv unfold_amm_conv ctxt)
val setup_abs_min_max = fold (SMT_Builtin.add_builtin_fun_ext'' o fst) defs
end
(** embedding of standard natural number operations into integer operations **)
local
val nat_embedding = @{lemma
"ALL n. nat (int n) = n"
"ALL i. i >= 0 --> int (nat i) = i"
"ALL i. i < 0 --> int (nat i) = 0"
by simp_all}
val simple_nat_ops = [
@{const less (nat)}, @{const less_eq (nat)},
@{const Suc}, @{const plus (nat)}, @{const minus (nat)}]
val mult_nat_ops =
[@{const times (nat)}, @{const div (nat)}, @{const mod (nat)}]
val nat_ops = simple_nat_ops @ mult_nat_ops
val nat_consts = nat_ops @ [@{const numeral (nat)},
@{const zero_class.zero (nat)}, @{const one_class.one (nat)}]
val nat_int_coercions = [@{const of_nat (int)}, @{const nat}]
val builtin_nat_ops = nat_int_coercions @ simple_nat_ops
val is_nat_const = member (op aconv) nat_consts
fun is_nat_const' @{const of_nat (int)} = true
| is_nat_const' t = is_nat_const t
val expands = map mk_meta_eq @{lemma
"0 = nat 0"
"1 = nat 1"
"(numeral :: num => nat) = (%i. nat (numeral i))"
"op < = (%a b. int a < int b)"
"op <= = (%a b. int a <= int b)"
"Suc = (%a. nat (int a + 1))"
"op + = (%a b. nat (int a + int b))"
"op - = (%a b. nat (int a - int b))"
"op * = (%a b. nat (int a * int b))"
"op div = (%a b. nat (int a div int b))"
"op mod = (%a b. nat (int a mod int b))"
by (fastforce simp add: nat_mult_distrib nat_div_distrib nat_mod_distrib)+}
val ints = map mk_meta_eq @{lemma
"int 0 = 0"
"int 1 = 1"
"int (Suc n) = int n + 1"
"int (n + m) = int n + int m"
"int (n - m) = int (nat (int n - int m))"
"int (n * m) = int n * int m"
"int (n div m) = int n div int m"
"int (n mod m) = int n mod int m"
by (auto simp add: int_mult zdiv_int zmod_int)}
val int_if = mk_meta_eq @{lemma
"int (if P then n else m) = (if P then int n else int m)"
by simp}
fun mk_number_eq ctxt i lhs =
let
val eq = SMT_Utils.mk_cequals lhs (Numeral.mk_cnumber @{ctyp int} i)
val tac =
Simplifier.simp_tac (put_simpset HOL_ss ctxt addsimps [@{thm Int.int_numeral}]) 1
in Goal.norm_result ctxt (Goal.prove_internal ctxt [] eq (K tac)) end
fun ite_conv cv1 cv2 =
Conv.combination_conv (Conv.combination_conv (Conv.arg_conv cv1) cv2) cv2
fun int_conv ctxt ct =
(case Thm.term_of ct of
@{const of_nat (int)} $ (n as (@{const numeral (nat)} $ _)) =>
Conv.rewr_conv (mk_number_eq ctxt (snd (HOLogic.dest_number n)) ct)
| @{const of_nat (int)} $ _ =>
(Conv.rewrs_conv ints then_conv Conv.sub_conv ints_conv ctxt) else_conv
(Conv.rewr_conv int_if then_conv
ite_conv (nat_conv ctxt) (int_conv ctxt)) else_conv
Conv.sub_conv (Conv.top_sweep_conv nat_conv) ctxt
| _ => Conv.no_conv) ct
and ints_conv ctxt = Conv.top_sweep_conv int_conv ctxt
and expand_conv ctxt =
SMT_Utils.if_conv (is_nat_const o Term.head_of)
(expand_head_conv (Conv.rewrs_conv expands) then_conv ints_conv ctxt)
(int_conv ctxt)
and nat_conv ctxt = SMT_Utils.if_exists_conv is_nat_const'
(Conv.top_sweep_conv expand_conv ctxt)
val uses_nat_int = Term.exists_subterm (member (op aconv) nat_int_coercions)
in
val nat_as_int_conv = nat_conv
fun add_nat_embedding thms =
if exists (uses_nat_int o Thm.prop_of) thms then (thms, nat_embedding)
else (thms, [])
val setup_nat_as_int =
SMT_Builtin.add_builtin_typ_ext (@{typ nat}, K true) #>
fold (SMT_Builtin.add_builtin_fun_ext' o Term.dest_Const) builtin_nat_ops
end
(** normalize numerals **)
local
(*
rewrite Numeral1 into 1
rewrite - 0 into 0
*)
fun is_irregular_number (Const (@{const_name numeral}, _) $ Const (@{const_name num.One}, _)) =
true
| is_irregular_number (Const (@{const_name uminus}, _) $ Const (@{const_name Groups.zero}, _)) =
true
| is_irregular_number _ =
false;
fun is_strange_number ctxt t = is_irregular_number t andalso SMT_Builtin.is_builtin_num ctxt t;
val proper_num_ss =
simpset_of (put_simpset HOL_ss @{context}
addsimps @{thms Num.numeral_One minus_zero})
fun norm_num_conv ctxt =
SMT_Utils.if_conv (is_strange_number ctxt)
(Simplifier.rewrite (put_simpset proper_num_ss ctxt)) Conv.no_conv
in
fun normalize_numerals_conv ctxt =
SMT_Utils.if_exists_conv (is_strange_number ctxt)
(Conv.top_sweep_conv norm_num_conv ctxt)
end
(** combined unfoldings and rewritings **)
fun unfold_conv ctxt =
rewrite_case_bool_conv ctxt then_conv
unfold_abs_min_max_conv ctxt then_conv
nat_as_int_conv ctxt then_conv
Thm.beta_conversion true
fun unfold1 ctxt = map (apsnd (Conv.fconv_rule (unfold_conv ctxt)))
fun burrow_ids f ithms =
let
val (is, thms) = split_list ithms
val (thms', extra_thms) = f thms
in (is ~~ thms') @ map (pair ~1) extra_thms end
fun unfold2 ctxt ithms =
ithms
|> map (apsnd (Conv.fconv_rule (normalize_numerals_conv ctxt)))
|> burrow_ids add_nat_embedding
(* overall normalization *)
type extra_norm = Proof.context -> thm list * thm list -> thm list * thm list
structure Extra_Norms = Generic_Data
(
type T = extra_norm SMT_Utils.dict
val empty = []
val extend = I
fun merge data = SMT_Utils.dict_merge fst data
)
fun add_extra_norm (cs, norm) =
Extra_Norms.map (SMT_Utils.dict_update (cs, norm))
fun apply_extra_norms ctxt ithms =
let
val cs = SMT_Config.solver_class_of ctxt
val es = SMT_Utils.dict_lookup (Extra_Norms.get (Context.Proof ctxt)) cs
in burrow_ids (fold (fn e => e ctxt) es o rpair []) ithms end
local
val ignored = member (op =) [@{const_name All}, @{const_name Ex},
@{const_name Let}, @{const_name If}, @{const_name HOL.eq}]
val schematic_consts_of =
let
fun collect (@{const SMT.trigger} $ p $ t) =
collect_trigger p #> collect t
| collect (t $ u) = collect t #> collect u
| collect (Abs (_, _, t)) = collect t
| collect (t as Const (n, _)) =
if not (ignored n) then Monomorph.add_schematic_consts_of t else I
| collect _ = I
and collect_trigger t =
let val dest = these o try HOLogic.dest_list
in fold (fold collect_pat o dest) (dest t) end
and collect_pat (Const (@{const_name SMT.pat}, _) $ t) = collect t
| collect_pat (Const (@{const_name SMT.nopat}, _) $ t) = collect t
| collect_pat _ = I
in (fn t => collect t Symtab.empty) end
in
fun monomorph ctxt xthms =
let val (xs, thms) = split_list xthms
in
map (pair 1) thms
|> Monomorph.monomorph schematic_consts_of ctxt
|> maps (uncurry (map o pair)) o map2 pair xs o map (map snd)
end
end
fun normalize iwthms ctxt =
iwthms
|> gen_normalize ctxt
|> unfold1 ctxt
|> monomorph ctxt
|> unfold2 ctxt
|> apply_extra_norms ctxt
|> rpair ctxt
val setup = Context.theory_map (
setup_atomize #>
setup_unfolded_quants #>
setup_trigger #>
setup_weight #>
setup_case_bool #>
setup_abs_min_max #>
setup_nat_as_int)
end