src/HOL/Lattices.thy
 author haftmann Wed Nov 15 17:05:40 2006 +0100 (2006-11-15) changeset 21381 79e065f2be95 parent 21312 1d39091a3208 child 21619 dea0914773f7 permissions -rw-r--r--
reworking of min/max lemmas
```     1 (*  Title:      HOL/Lattices.thy
```
```     2     ID:         \$Id\$
```
```     3     Author:     Tobias Nipkow
```
```     4 *)
```
```     5
```
```     6 header {* Lattices via Locales *}
```
```     7
```
```     8 theory Lattices
```
```     9 imports Orderings
```
```    10 begin
```
```    11
```
```    12 subsection{* Lattices *}
```
```    13
```
```    14 text{* This theory of lattice locales only defines binary sup and inf
```
```    15 operations. The extension to finite sets is done in theory @{text
```
```    16 Finite_Set}. In the longer term it may be better to define arbitrary
```
```    17 sups and infs via @{text THE}. *}
```
```    18
```
```    19 locale lower_semilattice = partial_order +
```
```    20   fixes inf :: "'a \<Rightarrow> 'a \<Rightarrow> 'a" (infixl "\<sqinter>" 70)
```
```    21   assumes inf_le1[simp]: "x \<sqinter> y \<sqsubseteq> x" and inf_le2[simp]: "x \<sqinter> y \<sqsubseteq> y"
```
```    22   and inf_least: "x \<sqsubseteq> y \<Longrightarrow> x \<sqsubseteq> z \<Longrightarrow> x \<sqsubseteq> y \<sqinter> z"
```
```    23
```
```    24 locale upper_semilattice = partial_order +
```
```    25   fixes sup :: "'a \<Rightarrow> 'a \<Rightarrow> 'a" (infixl "\<squnion>" 65)
```
```    26   assumes sup_ge1[simp]: "x \<sqsubseteq> x \<squnion> y" and sup_ge2[simp]: "y \<sqsubseteq> x \<squnion> y"
```
```    27   and sup_greatest: "y \<sqsubseteq> x \<Longrightarrow> z \<sqsubseteq> x \<Longrightarrow> y \<squnion> z \<sqsubseteq> x"
```
```    28
```
```    29 locale lattice = lower_semilattice + upper_semilattice
```
```    30
```
```    31 lemma (in lower_semilattice) inf_commute: "(x \<sqinter> y) = (y \<sqinter> x)"
```
```    32 by(blast intro: antisym inf_le1 inf_le2 inf_least)
```
```    33
```
```    34 lemma (in upper_semilattice) sup_commute: "(x \<squnion> y) = (y \<squnion> x)"
```
```    35 by(blast intro: antisym sup_ge1 sup_ge2 sup_greatest)
```
```    36
```
```    37 lemma (in lower_semilattice) inf_assoc: "(x \<sqinter> y) \<sqinter> z = x \<sqinter> (y \<sqinter> z)"
```
```    38 by(blast intro: antisym inf_le1 inf_le2 inf_least trans del:refl)
```
```    39
```
```    40 lemma (in upper_semilattice) sup_assoc: "(x \<squnion> y) \<squnion> z = x \<squnion> (y \<squnion> z)"
```
```    41 by(blast intro!: antisym sup_ge1 sup_ge2 intro: sup_greatest trans del:refl)
```
```    42
```
```    43 lemma (in lower_semilattice) inf_idem[simp]: "x \<sqinter> x = x"
```
```    44 by(blast intro: antisym inf_le1 inf_le2 inf_least refl)
```
```    45
```
```    46 lemma (in upper_semilattice) sup_idem[simp]: "x \<squnion> x = x"
```
```    47 by(blast intro: antisym sup_ge1 sup_ge2 sup_greatest refl)
```
```    48
```
```    49 lemma (in lower_semilattice) inf_left_idem[simp]: "x \<sqinter> (x \<sqinter> y) = x \<sqinter> y"
```
```    50 by (simp add: inf_assoc[symmetric])
```
```    51
```
```    52 lemma (in upper_semilattice) sup_left_idem[simp]: "x \<squnion> (x \<squnion> y) = x \<squnion> y"
```
```    53 by (simp add: sup_assoc[symmetric])
```
```    54
```
```    55 lemma (in lattice) inf_sup_absorb: "x \<sqinter> (x \<squnion> y) = x"
```
```    56 by(blast intro: antisym inf_le1 inf_least sup_ge1)
```
```    57
```
```    58 lemma (in lattice) sup_inf_absorb: "x \<squnion> (x \<sqinter> y) = x"
```
```    59 by(blast intro: antisym sup_ge1 sup_greatest inf_le1)
```
```    60
```
```    61 lemma (in lower_semilattice) inf_absorb: "x \<sqsubseteq> y \<Longrightarrow> x \<sqinter> y = x"
```
```    62 by(blast intro: antisym inf_le1 inf_least refl)
```
```    63
```
```    64 lemma (in upper_semilattice) sup_absorb: "x \<sqsubseteq> y \<Longrightarrow> x \<squnion> y = y"
```
```    65 by(blast intro: antisym sup_ge2 sup_greatest refl)
```
```    66
```
```    67
```
```    68 lemma (in lower_semilattice) less_eq_inf_conv [simp]:
```
```    69  "x \<sqsubseteq> y \<sqinter> z = (x \<sqsubseteq> y \<and> x \<sqsubseteq> z)"
```
```    70 by(blast intro: antisym inf_le1 inf_le2 inf_least refl trans)
```
```    71
```
```    72 lemmas (in lower_semilattice) below_inf_conv = less_eq_inf_conv
```
```    73   -- {* a duplicate for backward compatibility *}
```
```    74
```
```    75 lemma (in upper_semilattice) above_sup_conv[simp]:
```
```    76  "x \<squnion> y \<sqsubseteq> z = (x \<sqsubseteq> z \<and> y \<sqsubseteq> z)"
```
```    77 by(blast intro: antisym sup_ge1 sup_ge2 sup_greatest refl trans)
```
```    78
```
```    79
```
```    80 text{* Towards distributivity: if you have one of them, you have them all. *}
```
```    81
```
```    82 lemma (in lattice) distrib_imp1:
```
```    83 assumes D: "!!x y z. x \<sqinter> (y \<squnion> z) = (x \<sqinter> y) \<squnion> (x \<sqinter> z)"
```
```    84 shows "x \<squnion> (y \<sqinter> z) = (x \<squnion> y) \<sqinter> (x \<squnion> z)"
```
```    85 proof-
```
```    86   have "x \<squnion> (y \<sqinter> z) = (x \<squnion> (x \<sqinter> z)) \<squnion> (y \<sqinter> z)" by(simp add:sup_inf_absorb)
```
```    87   also have "\<dots> = x \<squnion> (z \<sqinter> (x \<squnion> y))" by(simp add:D inf_commute sup_assoc)
```
```    88   also have "\<dots> = ((x \<squnion> y) \<sqinter> x) \<squnion> ((x \<squnion> y) \<sqinter> z)"
```
```    89     by(simp add:inf_sup_absorb inf_commute)
```
```    90   also have "\<dots> = (x \<squnion> y) \<sqinter> (x \<squnion> z)" by(simp add:D)
```
```    91   finally show ?thesis .
```
```    92 qed
```
```    93
```
```    94 lemma (in lattice) distrib_imp2:
```
```    95 assumes D: "!!x y z. x \<squnion> (y \<sqinter> z) = (x \<squnion> y) \<sqinter> (x \<squnion> z)"
```
```    96 shows "x \<sqinter> (y \<squnion> z) = (x \<sqinter> y) \<squnion> (x \<sqinter> z)"
```
```    97 proof-
```
```    98   have "x \<sqinter> (y \<squnion> z) = (x \<sqinter> (x \<squnion> z)) \<sqinter> (y \<squnion> z)" by(simp add:inf_sup_absorb)
```
```    99   also have "\<dots> = x \<sqinter> (z \<squnion> (x \<sqinter> y))" by(simp add:D sup_commute inf_assoc)
```
```   100   also have "\<dots> = ((x \<sqinter> y) \<squnion> x) \<sqinter> ((x \<sqinter> y) \<squnion> z)"
```
```   101     by(simp add:sup_inf_absorb sup_commute)
```
```   102   also have "\<dots> = (x \<sqinter> y) \<squnion> (x \<sqinter> z)" by(simp add:D)
```
```   103   finally show ?thesis .
```
```   104 qed
```
```   105
```
```   106 text{* A package of rewrite rules for deciding equivalence wrt ACI: *}
```
```   107
```
```   108 lemma (in lower_semilattice) inf_left_commute: "x \<sqinter> (y \<sqinter> z) = y \<sqinter> (x \<sqinter> z)"
```
```   109 proof -
```
```   110   have "x \<sqinter> (y \<sqinter> z) = (y \<sqinter> z) \<sqinter> x" by (simp only: inf_commute)
```
```   111   also have "... = y \<sqinter> (z \<sqinter> x)" by (simp only: inf_assoc)
```
```   112   also have "z \<sqinter> x = x \<sqinter> z" by (simp only: inf_commute)
```
```   113   finally(back_subst) show ?thesis .
```
```   114 qed
```
```   115
```
```   116 lemma (in upper_semilattice) sup_left_commute: "x \<squnion> (y \<squnion> z) = y \<squnion> (x \<squnion> z)"
```
```   117 proof -
```
```   118   have "x \<squnion> (y \<squnion> z) = (y \<squnion> z) \<squnion> x" by (simp only: sup_commute)
```
```   119   also have "... = y \<squnion> (z \<squnion> x)" by (simp only: sup_assoc)
```
```   120   also have "z \<squnion> x = x \<squnion> z" by (simp only: sup_commute)
```
```   121   finally(back_subst) show ?thesis .
```
```   122 qed
```
```   123
```
```   124 lemma (in lower_semilattice) inf_left_idem: "x \<sqinter> (x \<sqinter> y) = x \<sqinter> y"
```
```   125 proof -
```
```   126   have "x \<sqinter> (x \<sqinter> y) = (x \<sqinter> x) \<sqinter> y" by(simp only:inf_assoc)
```
```   127   also have "\<dots> = x \<sqinter> y" by(simp)
```
```   128   finally show ?thesis .
```
```   129 qed
```
```   130
```
```   131 lemma (in upper_semilattice) sup_left_idem: "x \<squnion> (x \<squnion> y) = x \<squnion> y"
```
```   132 proof -
```
```   133   have "x \<squnion> (x \<squnion> y) = (x \<squnion> x) \<squnion> y" by(simp only:sup_assoc)
```
```   134   also have "\<dots> = x \<squnion> y" by(simp)
```
```   135   finally show ?thesis .
```
```   136 qed
```
```   137
```
```   138
```
```   139 lemmas (in lower_semilattice) inf_ACI =
```
```   140  inf_commute inf_assoc inf_left_commute inf_left_idem
```
```   141
```
```   142 lemmas (in upper_semilattice) sup_ACI =
```
```   143  sup_commute sup_assoc sup_left_commute sup_left_idem
```
```   144
```
```   145 lemmas (in lattice) ACI = inf_ACI sup_ACI
```
```   146
```
```   147
```
```   148 subsection{* Distributive lattices *}
```
```   149
```
```   150 locale distrib_lattice = lattice +
```
```   151   assumes sup_inf_distrib1: "x \<squnion> (y \<sqinter> z) = (x \<squnion> y) \<sqinter> (x \<squnion> z)"
```
```   152
```
```   153 lemma (in distrib_lattice) sup_inf_distrib2:
```
```   154  "(y \<sqinter> z) \<squnion> x = (y \<squnion> x) \<sqinter> (z \<squnion> x)"
```
```   155 by(simp add:ACI sup_inf_distrib1)
```
```   156
```
```   157 lemma (in distrib_lattice) inf_sup_distrib1:
```
```   158  "x \<sqinter> (y \<squnion> z) = (x \<sqinter> y) \<squnion> (x \<sqinter> z)"
```
```   159 by(rule distrib_imp2[OF sup_inf_distrib1])
```
```   160
```
```   161 lemma (in distrib_lattice) inf_sup_distrib2:
```
```   162  "(y \<squnion> z) \<sqinter> x = (y \<sqinter> x) \<squnion> (z \<sqinter> x)"
```
```   163 by(simp add:ACI inf_sup_distrib1)
```
```   164
```
```   165 lemmas (in distrib_lattice) distrib =
```
```   166   sup_inf_distrib1 sup_inf_distrib2 inf_sup_distrib1 inf_sup_distrib2
```
```   167
```
```   168
```
```   169 subsection {* min/max on linear orders as special case of inf/sup *}
```
```   170
```
```   171 interpretation min_max:
```
```   172   distrib_lattice ["op \<le>" "op <" "min \<Colon> 'a\<Colon>linorder \<Rightarrow> 'a \<Rightarrow> 'a" "max"]
```
```   173 apply unfold_locales
```
```   174 apply (simp add: min_def linorder_not_le order_less_imp_le)
```
```   175 apply (simp add: min_def linorder_not_le order_less_imp_le)
```
```   176 apply (simp add: min_def linorder_not_le order_less_imp_le)
```
```   177 apply (simp add: max_def linorder_not_le order_less_imp_le)
```
```   178 apply (simp add: max_def linorder_not_le order_less_imp_le)
```
```   179 unfolding min_def max_def by auto
```
```   180
```
```   181 lemmas le_maxI1 = min_max.sup_ge1
```
```   182 lemmas le_maxI2 = min_max.sup_ge2
```
```   183
```
```   184 lemmas max_ac = min_max.sup_assoc min_max.sup_commute
```
```   185                mk_left_commute[of max,OF min_max.sup_assoc min_max.sup_commute]
```
```   186
```
```   187 lemmas min_ac = min_max.inf_assoc min_max.inf_commute
```
```   188                mk_left_commute[of min,OF min_max.inf_assoc min_max.inf_commute]
```
```   189
```
```   190 text {* ML legacy bindings *}
```
```   191
```
```   192 ML {*
```
```   193 val Least_def = thm "Least_def";
```
```   194 val Least_equality = thm "Least_equality";
```
```   195 val min_def = thm "min_def";
```
```   196 val min_of_mono = thm "min_of_mono";
```
```   197 val max_def = thm "max_def";
```
```   198 val max_of_mono = thm "max_of_mono";
```
```   199 val min_leastL = thm "min_leastL";
```
```   200 val max_leastL = thm "max_leastL";
```
```   201 val min_leastR = thm "min_leastR";
```
```   202 val max_leastR = thm "max_leastR";
```
```   203 val le_max_iff_disj = thm "le_max_iff_disj";
```
```   204 val le_maxI1 = thm "le_maxI1";
```
```   205 val le_maxI2 = thm "le_maxI2";
```
```   206 val less_max_iff_disj = thm "less_max_iff_disj";
```
```   207 val max_less_iff_conj = thm "max_less_iff_conj";
```
```   208 val min_less_iff_conj = thm "min_less_iff_conj";
```
```   209 val min_le_iff_disj = thm "min_le_iff_disj";
```
```   210 val min_less_iff_disj = thm "min_less_iff_disj";
```
```   211 val split_min = thm "split_min";
```
```   212 val split_max = thm "split_max";
```
```   213 *}
```
```   214
```
```   215 end
```