src/HOL/Basic_BNF_LFPs.thy
 author haftmann Fri Jun 19 07:53:35 2015 +0200 (2015-06-19) changeset 60517 f16e4fb20652 parent 59819 dbec7f33093d child 61076 bdc1e2f0a86a permissions -rw-r--r--
separate class for notions specific for integral (semi)domains, in contrast to fields where these are trivial
```     1 (*  Title:      HOL/Basic_BNF_LFPs.thy
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```     2     Author:     Jasmin Blanchette, TU Muenchen
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```     3     Copyright   2014
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```     4
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```     5 Registration of basic types as BNF least fixpoints (datatypes).
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```     6 *)
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```     7
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```     8 theory Basic_BNF_LFPs
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```     9 imports BNF_Least_Fixpoint
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```    10 begin
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```    11
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```    12 definition xtor :: "'a \<Rightarrow> 'a" where
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```    13   "xtor x = x"
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```    14
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```    15 lemma xtor_map: "f (xtor x) = xtor (f x)"
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```    16   unfolding xtor_def by (rule refl)
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```    17
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```    18 lemma xtor_set: "f (xtor x) = f x"
```
```    19   unfolding xtor_def by (rule refl)
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```    20
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```    21 lemma xtor_rel: "R (xtor x) (xtor y) = R x y"
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```    22   unfolding xtor_def by (rule refl)
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```    23
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```    24 lemma xtor_induct: "(\<And>x. P (xtor x)) \<Longrightarrow> P z"
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```    25   unfolding xtor_def by assumption
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```    26
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```    27 lemma xtor_xtor: "xtor (xtor x) = x"
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```    28   unfolding xtor_def by (rule refl)
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```    29
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```    30 lemmas xtor_inject = xtor_rel[of "op ="]
```
```    31
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```    32 lemma xtor_rel_induct: "(\<And>x y. vimage2p id_bnf id_bnf R x y \<Longrightarrow> IR (xtor x) (xtor y)) \<Longrightarrow> R \<le> IR"
```
```    33   unfolding xtor_def vimage2p_def id_bnf_def by default
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```    34
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```    35 lemma Inl_def_alt: "Inl \<equiv> (\<lambda>a. xtor (id_bnf (Inl a)))"
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```    36   unfolding xtor_def id_bnf_def by (rule reflexive)
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```    37
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```    38 lemma Inr_def_alt: "Inr \<equiv> (\<lambda>a. xtor (id_bnf (Inr a)))"
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```    39   unfolding xtor_def id_bnf_def by (rule reflexive)
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```    40
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```    41 lemma Pair_def_alt: "Pair \<equiv> (\<lambda>a b. xtor (id_bnf (a, b)))"
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```    42   unfolding xtor_def id_bnf_def by (rule reflexive)
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```    43
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```    44 definition ctor_rec :: "'a \<Rightarrow> 'a" where
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```    45   "ctor_rec x = x"
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```    46
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```    47 lemma ctor_rec: "g = id \<Longrightarrow> ctor_rec f (xtor x) = f ((id_bnf \<circ> g \<circ> id_bnf) x)"
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```    48   unfolding ctor_rec_def id_bnf_def xtor_def comp_def id_def by hypsubst (rule refl)
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```    49
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```    50 lemma ctor_rec_def_alt: "f = ctor_rec (f \<circ> id_bnf)"
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```    51   unfolding ctor_rec_def id_bnf_def comp_def by (rule refl)
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```    52
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```    53 lemma ctor_rec_o_map: "ctor_rec f \<circ> g = ctor_rec (f \<circ> (id_bnf \<circ> g \<circ> id_bnf))"
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```    54   unfolding ctor_rec_def id_bnf_def comp_def by (rule refl)
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```    55
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```    56 lemma eq_fst_iff: "a = fst p \<longleftrightarrow> (\<exists>b. p = (a, b))"
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```    57   by (cases p) auto
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```    58
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```    59 lemma eq_snd_iff: "b = snd p \<longleftrightarrow> (\<exists>a. p = (a, b))"
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```    60   by (cases p) auto
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```    61
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```    62 lemma ex_neg_all_pos: "((\<exists>x. P x) \<Longrightarrow> Q) \<equiv> (\<And>x. P x \<Longrightarrow> Q)"
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```    63   by default blast+
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```    64
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```    65 lemma hypsubst_in_prems: "(\<And>x. y = x \<Longrightarrow> z = f x \<Longrightarrow> P) \<equiv> (z = f y \<Longrightarrow> P)"
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```    66   by default blast+
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```    67
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```    68 lemma isl_map_sum:
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```    69   "isl (map_sum f g s) = isl s"
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```    70   by (cases s) simp_all
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```    71
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```    72 lemma map_sum_sel:
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```    73   "isl s \<Longrightarrow> projl (map_sum f g s) = f (projl s)"
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```    74   "\<not> isl s \<Longrightarrow> projr (map_sum f g s) = g (projr s)"
```
```    75   by (case_tac [!] s) simp_all
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```    76
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```    77 lemma set_sum_sel:
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```    78   "isl s \<Longrightarrow> projl s \<in> setl s"
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```    79   "\<not> isl s \<Longrightarrow> projr s \<in> setr s"
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```    80   by (case_tac [!] s) (auto intro: setl.intros setr.intros)
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```    81
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```    82 lemma rel_sum_sel: "rel_sum R1 R2 a b = (isl a = isl b \<and>
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```    83   (isl a \<longrightarrow> isl b \<longrightarrow> R1 (projl a) (projl b)) \<and>
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```    84   (\<not> isl a \<longrightarrow> \<not> isl b \<longrightarrow> R2 (projr a) (projr b)))"
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```    85   by (cases a b rule: sum.exhaust[case_product sum.exhaust]) simp_all
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```    86
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```    87 lemma isl_transfer: "rel_fun (rel_sum A B) (op =) isl isl"
```
```    88   unfolding rel_fun_def rel_sum_sel by simp
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```    89
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```    90 lemma rel_prod_sel: "rel_prod R1 R2 p q = (R1 (fst p) (fst q) \<and> R2 (snd p) (snd q))"
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```    91   by (force simp: rel_prod.simps elim: rel_prod.cases)
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```    92
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```    93 ML_file "Tools/BNF/bnf_lfp_basic_sugar.ML"
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```    94
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```    95 ML_file "~~/src/HOL/Tools/Old_Datatype/old_size.ML"
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```    96
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```    97 lemma size_bool[code]: "size (b\<Colon>bool) = 0"
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```    98   by (cases b) auto
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```    99
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```   100 declare prod.size[no_atp]
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```   101
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```   102 lemmas size_nat = size_nat_def
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```   103
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```   104 hide_const (open) xtor ctor_rec
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```   105
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```   106 hide_fact (open)
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```   107   xtor_def xtor_map xtor_set xtor_rel xtor_induct xtor_xtor xtor_inject ctor_rec_def ctor_rec
```
```   108   ctor_rec_def_alt ctor_rec_o_map xtor_rel_induct Inl_def_alt Inr_def_alt Pair_def_alt
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```   109
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```   110 end
```