diff -r f1b39d77db00 -r ad57323fd4d6 RTree.thy
--- a/RTree.thy	Thu Dec 03 14:34:29 2015 +0800
+++ b/RTree.thy	Tue Dec 15 21:45:46 2015 +0800
@@ -1,5 +1,5 @@
 theory RTree
-imports "~~/src/HOL/Library/Transitive_Closure_Table"
+imports "~~/src/HOL/Library/Transitive_Closure_Table" Max
 begin
 
 section {* A theory of relational trees *}
@@ -10,7 +10,7 @@
 subsection {* Definitions *}
 
 text {*
-  In this theory, we are giving to give a notion of of `Relational Graph` and
+  In this theory, we are going to give a notion of of `Relational Graph` and
   its derived notion `Relational Tree`. Given a binary relation @{text "r"},
   the `Relational Graph of @{text "r"}` is the graph, the edges of which
   are those in @{text "r"}. In this way, any binary relation can be viewed
@@ -81,6 +81,10 @@
 
 definition "subtree r x = {y . (y, x) \<in> r^*}"
 
+definition "ancestors r x = {y. (x, y) \<in> r^+}"
+
+definition "root r x = (ancestors r x = {})"
+
 text {*
   The following @{text "edge_in r x"} is the set of edges
   contained in the sub-tree of @{text "x"}, with @{text "r"} as the underlying graph.
@@ -110,15 +114,26 @@
 qed
 
 text {*
-  The following lemma shows the means of @{term "edges_in"} from the other side, 
-  which says to for the edge @{text "(a,b)"} to be outside of the sub-tree of @{text "x"}, 
-  it is sufficient if @{text "b"} is.
+  The following lemma shows the meaning of @{term "edges_in"} from the other side, 
+  which says: for the edge @{text "(a,b)"} to be outside of the sub-tree of @{text "x"}, 
+  it is sufficient to show that @{text "b"} is.
 *}
 lemma edges_in_refutation:
   assumes "b \<notin> subtree r x"
   shows "(a, b) \<notin> edges_in r x"
   using assms by (unfold edges_in_def subtree_def, auto)
 
+definition "children r x = {y. (y, x) \<in> r}"
+
+locale fbranch =
+  fixes r
+  assumes fb: "\<forall> x \<in> Range r . finite (children r x)"
+
+locale fsubtree = fbranch + 
+   assumes wf: "wf r"
+
+(* ccc *)
+
 subsection {* Auxiliary lemmas *}
 
 lemma index_minimize:
@@ -171,8 +186,6 @@
 
 text {* Induction rule for @{text "rpath"}: *}
 
-print_statement rtrancl_path.induct
-
 lemma rpath_induct [consumes 1, case_names rbase rstep, induct pred: rpath]:
   assumes "rpath r x1 x2 x3"
     and "\<And>x. P x [] x"
@@ -181,6 +194,13 @@
   using assms[unfolded rpath_def]
   by (induct, auto simp:pred_of_def rpath_def)
 
+lemma rpathE: 
+  assumes "rpath r x xs y"
+  obtains (base) "y = x" "xs = []"
+     | (step) z zs where "(x, z) \<in> r" "rpath r z zs y" "xs = z#zs"
+  using assms
+  by (induct, auto)
+
 text {* Introduction rule for empty path *}
 lemma rbaseI [intro!]: 
   assumes "x = y"
@@ -282,6 +302,43 @@
 
 subsubsection {* Properites of @{text "edges_on"} *}
 
+lemma edges_on_unfold:
+  "edges_on (a # b # xs) = {(a, b)} \<union> edges_on (b # xs)" (is "?L = ?R")
+proof -
+  { fix c d
+    assume "(c, d) \<in> ?L"
+    then obtain l1 l2 where h: "(a # b # xs) = l1 @ [c, d] @ l2" 
+        by (auto simp:edges_on_def)
+    have "(c, d) \<in> ?R"
+    proof(cases "l1")
+      case Nil
+      with h have "(c, d) = (a, b)" by auto
+      thus ?thesis by auto
+    next
+      case (Cons e es)
+      from h[unfolded this] have "b#xs = es@[c, d]@l2" by auto
+      thus ?thesis by (auto simp:edges_on_def)
+    qed
+  } moreover
+  { fix c d
+    assume "(c, d) \<in> ?R"
+    moreover have "(a, b) \<in> ?L" 
+    proof -
+      have "(a # b # xs) = []@[a,b]@xs" by simp
+      hence "\<exists> l1 l2. (a # b # xs) = l1@[a,b]@l2" by auto
+      thus ?thesis by (unfold edges_on_def, simp)
+    qed
+    moreover {
+        assume "(c, d) \<in> edges_on (b#xs)"
+        then obtain l1 l2 where "b#xs = l1@[c, d]@l2" by (unfold edges_on_def, auto)
+        hence "a#b#xs = (a#l1)@[c,d]@l2" by simp
+        hence "\<exists> l1 l2. (a # b # xs) = l1@[c,d]@l2" by metis
+        hence "(c,d) \<in> ?L" by (unfold edges_on_def, simp)
+    }
+    ultimately have "(c, d) \<in> ?L" by auto
+  } ultimately show ?thesis by auto
+qed
+
 lemma edges_on_len:
   assumes "(a,b) \<in> edges_on l"
   shows "length l \<ge> 2"
@@ -289,6 +346,7 @@
   by (unfold edges_on_def, auto)
 
 text {* Elimination of @{text "edges_on"} for non-empty path *}
+
 lemma edges_on_consE [elim, cases set:edges_on]:
   assumes "(a,b) \<in> edges_on (x#xs)"
   obtains (head)  xs' where "x = a" and "xs = b#xs'"
@@ -384,6 +442,23 @@
   qed
 qed (unfold rpath_def, auto intro!:Transitive_Closure_Table.rtrancl_path.base)
 
+lemma edges_on_rpathI:
+  assumes "edges_on (a#xs@[b]) \<subseteq> r"
+  shows "rpath r a (xs@[b]) b"
+  using assms
+proof(induct xs arbitrary: a b)
+  case Nil
+  moreover have "(a, b) \<in> edges_on (a # [] @ [b])"
+      by (unfold edges_on_def, auto)
+  ultimately have "(a, b) \<in> r" by auto
+  thus ?case by auto
+next
+  case (Cons x xs a b)
+  from this(2) have "edges_on (x # xs @ [b]) \<subseteq> r" by (simp add:edges_on_unfold)
+  from Cons(1)[OF this] have " rpath r x (xs @ [b]) b" .
+  moreover from Cons(2) have "(a, x) \<in> r" by (auto simp:edges_on_unfold)
+  ultimately show ?case by (auto)
+qed
 
 text {*
   The following lemma extracts the path from @{text "x"} to @{text "y"}
@@ -416,8 +491,32 @@
   thus ?thesis by (simp add: pred_of_star star_2_pstar)
 qed
 
+lemma subtree_transfer:
+  assumes "a \<in> subtree r1 a'"
+  and "r1 \<subseteq> r2"
+  shows "a \<in> subtree r2 a'"
+proof -
+  from assms(1)[unfolded subtree_def] 
+  have "(a, a') \<in> r1^*" by auto
+  from star_rpath[OF this]
+  obtain xs where rp: "rpath r1 a xs a'" by blast
+  hence "rpath r2 a xs a'"
+  proof(rule rpath_transfer)
+    from rpath_edges_on[OF rp] and assms(2)
+    show "edges_on (a # xs) \<subseteq> r2" by simp
+  qed
+  from rpath_star[OF this]
+  show ?thesis by (auto simp:subtree_def)
+qed
+
+lemma subtree_rev_transfer:
+  assumes "a \<notin> subtree r2 a'"
+  and "r1 \<subseteq> r2"
+  shows "a \<notin> subtree r1 a'"
+  using assms and subtree_transfer by metis
+
 text {*
-  The following lemmas establishes a relation from pathes in @{text "r"}
+  The following lemmas establishes a relation from paths in @{text "r"}
   to @{text "r^+"} relation.
 *}
 lemma rpath_plus: 
@@ -438,7 +537,50 @@
   qed
 qed
 
-subsubsection {* Properties of @{text "subtree"} *}
+lemma plus_rpath: 
+  assumes "(x, y) \<in> r^+"
+  obtains xs where "rpath r x xs y" and "xs \<noteq> []"
+proof -
+  from assms
+  show ?thesis
+  proof(cases rule:converse_tranclE[consumes 1])
+    case 1
+    hence "rpath r x [y] y" by auto
+    from that[OF this] show ?thesis by auto
+  next
+    case (2 z)
+    from 2(2) have "(z, y) \<in> r^*" by auto
+    from star_rpath[OF this] obtain xs where "rpath r z xs y" by auto
+    from rstepI[OF 2(1) this]
+    have "rpath r x (z # xs) y" .
+    from that[OF this] show ?thesis by auto
+  qed
+qed
+
+subsubsection {* Properties of @{text "subtree"} and @{term "ancestors"}*}
+
+lemma ancestors_subtreeI:
+  assumes "b \<in> ancestors r a"
+  shows "a \<in> subtree r b"
+  using assms by (auto simp:subtree_def ancestors_def)
+
+lemma subtreeE:
+  assumes "a \<in> subtree r b"
+  obtains "a = b"
+      | "a \<noteq> b" and "b \<in> ancestors r a"
+proof -
+  from assms have "(a, b) \<in> r^*" by (auto simp:subtree_def)
+  from rtranclD[OF this]
+  have " a = b \<or> a \<noteq> b \<and> (a, b) \<in> r\<^sup>+" .
+  with that[unfolded ancestors_def] show ?thesis by auto
+qed
+
+lemma subtree_ancestorsI:
+  assumes "a \<in> subtree r b"
+  and "a \<noteq> b"
+  shows "b \<in> ancestors r a"
+  using assms
+  by (auto elim!:subtreeE)
 
 text {*
   @{text "subtree"} is mono with respect to the underlying graph.
@@ -513,6 +655,55 @@
   } ultimately show ?thesis by auto
 qed
 
+(* ddd *)
+lemma subset_del_subtree_outside: (* ddd *)
+    assumes "Range r' \<inter> subtree r x = {}" 
+    shows "subtree (r - r') x = (subtree r x)" 
+proof -
+  { fix c
+    assume "c \<in> (subtree r x)"
+    hence "(c, x) \<in> r^*" by (auto simp:subtree_def)
+    hence "c \<in> subtree (r - r') x"
+    proof(rule star_rpath)
+      fix xs
+      assume rp: "rpath r c xs x"
+      show ?thesis
+      proof -
+        from rp
+        have "rpath  (r - r') c xs x"
+        proof(rule rpath_transfer)
+          from rpath_edges_on[OF rp] have "edges_on (c # xs) \<subseteq> r" .
+          moreover {
+              fix a b
+              assume h: "(a, b) \<in> r'"
+              have "(a, b) \<notin> edges_on (c#xs)"
+              proof
+                assume "(a, b) \<in> edges_on (c # xs)"
+                then obtain l1 l2 where "c#xs = (l1@[a])@[b]@l2" by (auto simp:edges_on_def)
+                hence "tl (c#xs) = tl (l1@[a,b]@l2)" by simp
+                then obtain l1' where eq_xs_b: "xs = l1'@[b]@l2" by (cases l1, auto)
+                from rp[unfolded this]
+                show False
+                proof(rule rpath_appendE)
+                  assume "rpath r b l2 x"
+                  from rpath_star[OF this]
+                  have "b \<in> subtree r x" by (auto simp:subtree_def)
+                  with assms (1) and h show ?thesis by (auto)
+                qed
+             qed
+         } ultimately show "edges_on (c # xs) \<subseteq> r - r'" by auto
+        qed
+        thus ?thesis by (rule rpath_star[elim_format], auto simp:subtree_def)
+      qed
+    qed
+  } moreover {
+    fix c
+    assume "c \<in> subtree (r - r') x"
+    moreover have "... \<subseteq> (subtree r x)" by (rule subtree_mono, auto)
+    ultimately have "c \<in> (subtree r x)" by auto
+  } ultimately show ?thesis by auto
+qed
+
 lemma subtree_insert_ext:
     assumes "b \<in> subtree r x"
     shows "subtree (r \<union> {(a, b)}) x = (subtree r x) \<union> (subtree r a)" 
@@ -524,11 +715,138 @@
     using assms
     by (auto simp:subtree_def rtrancl_insert)
 
+lemma set_add_rootI:
+  assumes "root r a"
+  and "a \<notin> Domain r1"
+  shows "root (r \<union> r1) a"
+proof -
+  let ?r = "r \<union> r1"
+  { fix a'
+    assume "a' \<in> ancestors ?r a"
+    hence "(a, a') \<in> ?r^+" by (auto simp:ancestors_def)
+    from tranclD[OF this] obtain z where "(a, z) \<in> ?r" by auto
+    moreover have "(a, z) \<notin> r"
+    proof
+      assume "(a, z) \<in> r"
+      with assms(1) show False 
+        by (auto simp:root_def ancestors_def)
+    qed
+    ultimately have "(a, z) \<in> r1" by auto
+    with assms(2) 
+    have False by (auto)
+  } thus ?thesis by (auto simp:root_def)
+qed
+
+lemma ancestors_mono:
+  assumes "r1 \<subseteq> r2"
+  shows "ancestors r1 x \<subseteq> ancestors r2 x"
+proof
+ fix a
+ assume "a \<in> ancestors r1 x"
+ hence "(x, a) \<in> r1^+" by (auto simp:ancestors_def)
+ from plus_rpath[OF this] obtain xs where 
+    h: "rpath r1 x xs a" "xs \<noteq> []" .
+ have "rpath r2 x xs a"
+ proof(rule rpath_transfer[OF h(1)])
+  from rpath_edges_on[OF h(1)] and assms
+  show "edges_on (x # xs) \<subseteq> r2" by auto
+ qed
+ from rpath_plus[OF this h(2)]
+ show "a \<in> ancestors r2 x" by (auto simp:ancestors_def)
+qed
+
+lemma subtree_refute:
+  assumes "x \<notin> ancestors r y"
+  and "x \<noteq> y"
+  shows "y \<notin> subtree r x"
+proof
+   assume "y \<in> subtree r x"
+   thus False
+     by(elim subtreeE, insert assms, auto)
+qed
+
 subsubsection {* Properties about relational trees *}
 
 context rtree 
 begin
 
+lemma ancestors_headE:
+  assumes "c \<in> ancestors r a"
+  assumes "(a, b) \<in> r"
+  obtains "b = c"
+     |   "c \<in> ancestors r b"
+proof -
+  from assms(1) 
+  have "(a, c) \<in> r^+" by (auto simp:ancestors_def)
+  hence "b = c \<or> c \<in> ancestors r b"
+  proof(cases rule:converse_tranclE[consumes 1])
+    case 1
+    with assms(2) and sgv have "b = c" by (auto simp:single_valued_def)
+    thus ?thesis by auto
+  next
+    case (2 y)
+    from 2(1) and assms(2) and sgv have "y = b" by (auto simp:single_valued_def)
+    from 2(2)[unfolded this] have "c \<in> ancestors r b" by (auto simp:ancestors_def)
+    thus ?thesis by auto
+  qed
+  with that show ?thesis by metis
+qed
+
+lemma ancestors_accum:
+  assumes "(a, b) \<in> r"
+  shows "ancestors r a = ancestors r b \<union> {b}"
+proof -
+  { fix c
+    assume "c \<in> ancestors r a"
+    hence "(a, c) \<in> r^+" by (auto simp:ancestors_def)
+    hence "c \<in> ancestors r b \<union> {b}"
+    proof(cases rule:converse_tranclE[consumes 1])
+      case 1
+      with sgv assms have "c = b" by (unfold single_valued_def, auto)
+      thus ?thesis by auto
+    next
+      case (2 c')
+      with sgv assms have "c' = b" by (unfold single_valued_def, auto)
+      from 2(2)[unfolded this]
+      show ?thesis by (auto simp:ancestors_def)
+    qed
+  } moreover {
+    fix c
+    assume "c \<in> ancestors r b \<union> {b}"
+    hence "c = b \<or> c \<in> ancestors r b" by auto
+    hence "c \<in> ancestors r a"
+    proof
+      assume "c = b"
+      from assms[folded this] 
+      show ?thesis by (auto simp:ancestors_def)
+    next
+      assume "c \<in> ancestors r b"
+      with assms show ?thesis by (auto simp:ancestors_def)
+    qed
+  } ultimately show ?thesis by auto
+qed
+
+lemma rootI:
+  assumes h: "\<And> x'. x' \<noteq> x \<Longrightarrow> x \<notin> subtree r' x'"
+  and "r' \<subseteq> r"
+  shows "root r' x"
+proof -
+  from acyclic_subset[OF acl assms(2)]
+  have acl': "acyclic r'" .
+  { fix x'
+    assume "x' \<in> ancestors r' x"
+    hence h1: "(x, x') \<in> r'^+" by (auto simp:ancestors_def)
+    have "x' \<noteq> x"
+    proof
+      assume eq_x: "x' = x"
+      from h1[unfolded this] and acl'
+      show False by (auto simp:acyclic_def)
+    qed
+    moreover from h1 have "x \<in> subtree r' x'" by (auto simp:subtree_def)
+    ultimately have False using h by auto
+  } thus ?thesis by (auto simp:root_def)
+qed
+
 lemma rpath_overlap_oneside: (* ddd *)
   assumes "rpath r x xs1 x1"
   and "rpath r x xs2 x2"
@@ -953,6 +1271,435 @@
   ultimately show ?thesis by auto
 qed 
 
+lemma  set_del_rootI:
+  assumes "r1 \<subseteq> r"
+  and "a \<in> Domain r1"
+  shows "root (r - r1) a"
+proof -
+   let ?r = "r - r1"
+  { fix a' 
+    assume neq: "a' \<noteq> a"
+    have "a \<notin> subtree ?r a'"
+    proof
+      assume "a \<in> subtree ?r a'"
+      hence "(a, a') \<in> ?r^*" by (auto simp:subtree_def)
+      from star_rpath[OF this] obtain xs
+      where rp: "rpath ?r a xs a'" by auto
+      from rpathE[OF this] and neq
+      obtain z zs where h: "(a, z) \<in> ?r" "rpath ?r z zs a'" "xs = z#zs" by auto
+      from assms(2) obtain z' where z'_in: "(a, z') \<in> r1" by (auto simp:DomainE)
+      with assms(1) have "(a, z') \<in> r" by auto
+      moreover from h(1) have "(a, z) \<in> r" by simp 
+      ultimately have "z' = z" using sgv by (auto simp:single_valued_def)
+      from z'_in[unfolded this] and h(1) show False by auto
+   qed
+  } thus ?thesis by (intro rootI, auto)
+qed
+
+lemma edge_del_no_rootI:
+  assumes "(a, b) \<in> r"
+  shows "root (r - {(a, b)}) a"
+  by (rule set_del_rootI, insert assms, auto)
+
+lemma ancestors_children_unique:
+  assumes "z1 \<in> ancestors r x \<inter> children r y"
+  and "z2 \<in> ancestors r x \<inter> children r y"
+  shows "z1 = z2"
+proof -
+  from assms have h:
+     "(x, z1) \<in> r^+" "(z1, y) \<in> r" 
+     "(x, z2) \<in> r^+" "(z2, y) \<in> r" 
+  by (auto simp:ancestors_def children_def)
+
+  -- {* From this, a path containing @{text "z1"} is obtained. *}
+  from plus_rpath[OF h(1)] obtain xs1 
+     where h1: "rpath r x xs1 z1" "xs1 \<noteq> []" by auto
+  from rpath_nnl_lastE[OF this] obtain xs1' where eq_xs1: "xs1 = xs1' @ [z1]"
+    by auto
+  from h(2) have h2: "rpath r z1 [y] y" by auto
+  from rpath_appendI[OF h1(1) h2, unfolded eq_xs1]
+  have rp1: "rpath r x (xs1' @ [z1, y]) y" by simp
+
+  -- {* Then, another path containing @{text "z2"} is obtained. *}
+  from plus_rpath[OF h(3)] obtain xs2
+     where h3: "rpath r x xs2 z2" "xs2 \<noteq> []" by auto
+  from rpath_nnl_lastE[OF this] obtain xs2' where eq_xs2: "xs2 = xs2' @ [z2]"
+    by auto
+  from h(4) have h4: "rpath r z2 [y] y" by auto
+  from rpath_appendI[OF h3(1) h4, unfolded eq_xs2]
+     have "rpath r x (xs2' @ [z2, y]) y" by simp
+
+  -- {* Finally @{text "z1 = z2"} is proved by uniqueness of path. *}
+  from rpath_unique[OF rp1 this]
+  have "xs1' @ [z1, y] = xs2' @ [z2, y]" .
+  thus ?thesis by auto
+qed
+
+lemma ancestors_childrenE:
+  assumes "y \<in> ancestors r x"
+  obtains "x \<in> children r y"
+      | z where "z \<in> ancestors r x \<inter> children r y"
+proof -
+  from assms(1) have "(x, y) \<in> r^+" by (auto simp:ancestors_def)
+  from tranclD2[OF this] obtain z where 
+     h: "(x, z) \<in> r\<^sup>*" "(z, y) \<in> r" by auto
+  from h(1)
+  show ?thesis
+  proof(cases rule:rtranclE)
+    case base
+    from h(2)[folded this] have "x \<in> children r y" 
+              by (auto simp:children_def)
+    thus ?thesis by (intro that, auto)
+  next
+    case (step u)
+    hence "z \<in> ancestors r x" by (auto simp:ancestors_def)
+    moreover from h(2) have "z \<in> children r y" 
+              by (auto simp:children_def)
+    ultimately show ?thesis by (intro that, auto)
+  qed
+qed
+
+
+end (* of rtree *)
+
+lemma subtree_children:
+  "subtree r x = {x} \<union> (\<Union> (subtree r ` (children r x)))" (is "?L = ?R")
+proof -
+  { fix z
+    assume "z \<in> ?L"
+    hence "z \<in> ?R"
+    proof(cases rule:subtreeE[consumes 1])
+      case 2
+      hence "(z, x) \<in> r^+" by (auto simp:ancestors_def)
+      thus ?thesis
+      proof(rule tranclE)
+        assume "(z, x) \<in> r"
+        hence "z \<in> children r x" by (unfold children_def, auto)
+        moreover have "z \<in> subtree r z" by (auto simp:subtree_def)
+        ultimately show ?thesis by auto
+      next
+        fix c
+        assume h: "(z, c) \<in> r\<^sup>+" "(c, x) \<in> r"
+        hence "c \<in> children r x" by (auto simp:children_def)
+        moreover from h have "z \<in> subtree r c" by (auto simp:subtree_def)
+        ultimately show ?thesis by auto
+      qed
+    qed auto
+  } moreover {
+    fix z
+    assume h: "z \<in> ?R"
+    have "x \<in> subtree r x" by (auto simp:subtree_def)
+    moreover {
+       assume "z \<in> \<Union>(subtree r ` children r x)"
+       then obtain y where "(y, x) \<in> r" "(z, y) \<in> r^*" 
+        by (auto simp:subtree_def children_def)
+       hence "(z, x) \<in> r^*" by auto
+       hence "z \<in> ?L" by (auto simp:subtree_def)
+    } ultimately have "z \<in> ?L" using h by auto
+  } ultimately show ?thesis by auto
+qed
+
+context fsubtree 
+begin
+  
+lemma finite_subtree:
+  shows "finite (subtree r x)"
+proof(induct rule:wf_induct[OF wf])
+  case (1 x)
+  have "finite (\<Union>(subtree r ` children r x))"
+  proof(rule finite_Union)
+    show "finite (subtree r ` children r x)"
+    proof(cases "children r x = {}")
+      case True
+      thus ?thesis by auto
+    next
+      case False
+      hence "x \<in> Range r" by (auto simp:children_def)
+      from fb[rule_format, OF this] 
+      have "finite (children r x)" .
+      thus ?thesis by (rule finite_imageI)
+    qed
+  next
+    fix M 
+    assume "M \<in> subtree r ` children r x"
+    then obtain y where h: "y \<in> children r x" "M = subtree r y" by auto
+    hence "(y, x) \<in> r" by (auto simp:children_def)
+    from 1[rule_format, OF this, folded h(2)]
+    show "finite M" .
+  qed
+  thus ?case
+    by (unfold subtree_children finite_Un, auto)
+qed
+
 end
 
+definition "pairself f = (\<lambda>(a, b). (f a, f b))"
+
+definition "rel_map f r = (pairself f ` r)"
+
+lemma rel_mapE: 
+  assumes "(a, b) \<in> rel_map f r"
+  obtains c d 
+  where "(c, d) \<in> r" "(a, b) = (f c, f d)"
+  using assms
+  by (unfold rel_map_def pairself_def, auto)
+
+lemma rel_mapI: 
+  assumes "(a, b) \<in> r"
+    and "c = f a"
+    and "d = f b"
+  shows "(c, d) \<in> rel_map f r"
+  using assms
+  by (unfold rel_map_def pairself_def, auto)
+
+lemma map_appendE:
+  assumes "map f zs = xs @ ys"
+  obtains xs' ys' 
+  where "zs = xs' @ ys'" "xs = map f xs'" "ys = map f ys'"
+proof -
+  have "\<exists> xs' ys'. zs = xs' @ ys' \<and> xs = map f xs' \<and> ys = map f ys'"
+  using assms
+  proof(induct xs arbitrary:zs ys)
+    case (Nil zs ys)
+    thus ?case by auto
+  next
+    case (Cons x xs zs ys)
+    note h = this
+    show ?case
+    proof(cases zs)
+      case (Cons e es)
+      with h have eq_x: "map f es = xs @ ys" "x = f e" by auto
+      from h(1)[OF this(1)]
+      obtain xs' ys' where "es = xs' @ ys'" "xs = map f xs'" "ys = map f ys'"
+        by blast
+      with Cons eq_x
+      have "zs = (e#xs') @ ys' \<and> x # xs = map f (e#xs') \<and> ys = map f ys'" by auto
+      thus ?thesis by metis
+    qed (insert h, auto)
+  qed
+  thus ?thesis by (auto intro!:that)
+qed
+
+lemma rel_map_mono:
+  assumes "r1 \<subseteq> r2"
+  shows "rel_map f r1 \<subseteq> rel_map f r2"
+  using assms
+  by (auto simp:rel_map_def pairself_def)
+
+lemma rel_map_compose [simp]:
+    shows "rel_map f1 (rel_map f2 r) = rel_map (f1 o f2) r"
+    by (auto simp:rel_map_def pairself_def)
+
+lemma edges_on_map: "edges_on (map f xs) = rel_map f (edges_on xs)"
+proof -
+  { fix a b
+    assume "(a, b) \<in> edges_on (map f xs)"
+    then obtain l1 l2 where eq_map: "map f xs = l1 @ [a, b] @ l2" 
+      by (unfold edges_on_def, auto)
+    hence "(a, b) \<in> rel_map f (edges_on xs)"
+      by (auto elim!:map_appendE intro!:rel_mapI simp:edges_on_def)
+  } moreover { 
+    fix a b
+    assume "(a, b) \<in> rel_map f (edges_on xs)"
+    then obtain c d where 
+        h: "(c, d) \<in> edges_on xs" "(a, b) = (f c, f d)" 
+             by (elim rel_mapE, auto)
+    then obtain l1 l2 where
+        eq_xs: "xs = l1 @ [c, d] @ l2" 
+             by (auto simp:edges_on_def)
+    hence eq_map: "map f xs = map f l1 @ [f c, f d] @ map f l2" by auto
+    have "(a, b) \<in> edges_on (map f xs)"
+    proof -
+      from h(2) have "[f c, f d] = [a, b]" by simp
+      from eq_map[unfolded this] show ?thesis by (auto simp:edges_on_def)
+    qed
+  } ultimately show ?thesis by auto
+qed
+
+lemma image_id:
+  assumes "\<And> x. x \<in> A \<Longrightarrow> f x = x"
+  shows "f ` A = A"
+  using assms by (auto simp:image_def)
+
+lemma rel_map_inv_id:
+  assumes "inj_on f ((Domain r) \<union> (Range r))"
+  shows "(rel_map (inv_into ((Domain r) \<union> (Range r)) f \<circ> f) r) = r"
+proof -
+ let ?f = "(inv_into (Domain r \<union> Range r) f \<circ> f)"
+ {
+  fix a b
+  assume h0: "(a, b) \<in> r"
+  have "pairself ?f (a, b) = (a, b)"
+  proof -
+    from assms h0 have "?f a = a" by (auto intro:inv_into_f_f)
+    moreover have "?f b = b"
+      by (insert h0, simp, intro inv_into_f_f[OF assms], auto intro!:RangeI)
+    ultimately show ?thesis by (auto simp:pairself_def)
+  qed
+ } thus ?thesis by (unfold rel_map_def, intro image_id, case_tac x, auto)
+qed 
+
+lemma rel_map_acyclic:
+  assumes "acyclic r"
+  and "inj_on f ((Domain r) \<union> (Range r))"
+  shows "acyclic (rel_map f r)"
+proof -
+  let ?D = "Domain r \<union> Range r"
+  { fix a 
+    assume "(a, a) \<in> (rel_map f r)^+" 
+    from plus_rpath[OF this]
+    obtain xs where rp: "rpath (rel_map f r) a xs a" "xs \<noteq> []" by auto
+    from rpath_nnl_lastE[OF this] obtain xs' where eq_xs: "xs = xs'@[a]" by auto
+    from rpath_edges_on[OF rp(1)]
+    have h: "edges_on (a # xs) \<subseteq> rel_map f r" .
+    from edges_on_map[of "inv_into ?D f" "a#xs"]
+    have "edges_on (map (inv_into ?D f) (a # xs)) = rel_map (inv_into ?D f) (edges_on (a # xs))" .
+    with rel_map_mono[OF h, of "inv_into ?D f"]
+    have "edges_on (map (inv_into ?D f) (a # xs)) \<subseteq> rel_map ((inv_into ?D f) o f) r" by simp
+    from this[unfolded eq_xs]
+    have subr: "edges_on (map (inv_into ?D f) (a # xs' @ [a])) \<subseteq> rel_map (inv_into ?D f \<circ> f) r" .
+    have "(map (inv_into ?D f) (a # xs' @ [a])) = (inv_into ?D f a) # map (inv_into ?D f) xs' @ [inv_into ?D f a]"
+      by simp
+    from edges_on_rpathI[OF subr[unfolded this]]
+    have "rpath (rel_map (inv_into ?D f \<circ> f) r) 
+                      (inv_into ?D f a) (map (inv_into ?D f) xs' @ [inv_into ?D f a]) (inv_into ?D f a)" .
+    hence "(inv_into ?D f a, inv_into ?D f a) \<in> (rel_map (inv_into ?D f \<circ> f) r)^+"
+        by (rule rpath_plus, simp)
+    moreover have "(rel_map (inv_into ?D f \<circ> f) r) = r" by (rule rel_map_inv_id[OF assms(2)])
+    moreover note assms(1) 
+    ultimately have False by (unfold acyclic_def, auto)
+  } thus ?thesis by (auto simp:acyclic_def)
+qed
+
+lemma relpow_mult: 
+  "((r::'a rel) ^^ m) ^^ n = r ^^ (m*n)"
+proof(induct n arbitrary:m)
+  case (Suc k m)
+  thus ?case
+  proof -
+    have h: "(m * k + m) = (m + m * k)" by auto
+    show ?thesis 
+      apply (simp add:Suc relpow_add[symmetric])
+      by (unfold h, simp)
+  qed
+qed simp
+
+lemma compose_relpow_2:
+  assumes "r1 \<subseteq> r"
+  and "r2 \<subseteq> r"
+  shows "r1 O r2 \<subseteq> r ^^ (2::nat)"
+proof -
+  { fix a b
+    assume "(a, b) \<in> r1 O r2"
+    then obtain e where "(a, e) \<in> r1" "(e, b) \<in> r2"
+      by auto
+    with assms have "(a, e) \<in> r" "(e, b) \<in> r" by auto
+    hence "(a, b) \<in> r ^^ (Suc (Suc 0))" by auto
+  } thus ?thesis by (auto simp:numeral_2_eq_2)
+qed
+
+lemma acyclic_compose:
+  assumes "acyclic r"
+  and "r1 \<subseteq> r"
+  and "r2 \<subseteq> r"
+  shows "acyclic (r1 O r2)"
+proof -
+  { fix a
+    assume "(a, a) \<in> (r1 O r2)^+"
+    from trancl_mono[OF this compose_relpow_2[OF assms(2, 3)]]
+    have "(a, a) \<in> (r ^^ 2) ^+" .
+    from trancl_power[THEN iffD1, OF this]
+    obtain n where h: "(a, a) \<in> (r ^^ 2) ^^ n" "n > 0" by blast
+    from this(1)[unfolded relpow_mult] have h2: "(a, a) \<in> r ^^ (2 * n)" .
+    have "(a, a) \<in> r^+" 
+    proof(cases rule:trancl_power[THEN iffD2])
+      from h(2) h2 show "\<exists>n>0. (a, a) \<in> r ^^ n" 
+        by (rule_tac x = "2*n" in exI, auto)
+    qed
+    with assms have "False" by (auto simp:acyclic_def)
+  } thus ?thesis by (auto simp:acyclic_def)
+qed
+
+lemma children_compose_unfold: 
+  "children (r1 O r2) x = \<Union> (children r1 ` (children r2 x))"
+  by (auto simp:children_def)
+
+lemma fbranch_compose:
+  assumes "fbranch r1"
+  and "fbranch r2"
+  shows "fbranch (r1 O r2)"
+proof -
+  {  fix x
+     assume "x\<in>Range (r1 O r2)"
+     then obtain y z where h: "(y, z) \<in> r1" "(z, x) \<in> r2" by auto
+     have "finite (children (r1 O r2) x)"
+     proof(unfold children_compose_unfold, rule finite_Union)
+      show "finite (children r1 ` children r2 x)"
+      proof(rule finite_imageI)
+        from h(2) have "x \<in> Range r2" by auto
+        from assms(2)[unfolded fbranch_def, rule_format, OF this]
+        show "finite (children r2 x)" .
+      qed
+     next
+       fix M
+       assume "M \<in> children r1 ` children r2 x"
+       then obtain y where h1: "y \<in> children r2 x" "M = children r1 y" by auto
+       show "finite M"
+       proof(cases "children r1 y = {}")
+          case True
+          with h1(2) show ?thesis by auto
+       next
+          case False
+          hence "y \<in> Range r1" by (unfold children_def, auto)
+          from assms(1)[unfolded fbranch_def, rule_format, OF this, folded h1(2)]
+          show ?thesis .
+       qed
+     qed
+  } thus ?thesis by (unfold fbranch_def, auto)
+qed
+
+lemma finite_fbranchI:
+  assumes "finite r"
+  shows "fbranch r"
+proof -
+  { fix x 
+    assume "x \<in>Range r"
+    have "finite (children r x)"
+    proof -
+      have "{y. (y, x) \<in> r} \<subseteq> Domain r" by (auto)
+      from rev_finite_subset[OF finite_Domain[OF assms] this]
+      have "finite {y. (y, x) \<in> r}" .
+      thus ?thesis by (unfold children_def, simp)
+    qed
+  } thus ?thesis by (auto simp:fbranch_def)
+qed
+
+lemma subset_fbranchI:
+  assumes "fbranch r1"
+  and "r2 \<subseteq> r1"
+  shows "fbranch r2"
+proof -
+  { fix x
+    assume "x \<in>Range r2"
+    with assms(2) have "x \<in> Range r1" by auto
+    from assms(1)[unfolded fbranch_def, rule_format, OF this]
+    have "finite (children r1 x)" .
+    hence "finite (children r2 x)"
+    proof(rule rev_finite_subset)
+      from assms(2)
+      show "children r2 x \<subseteq> children r1 x" by (auto simp:children_def)
+    qed
+  } thus ?thesis by (auto simp:fbranch_def)
+qed
+
+lemma children_subtree: 
+  shows "children r x \<subseteq> subtree r x"
+  by (auto simp:children_def subtree_def)
+
+lemma children_union_kept:
+  assumes "x \<notin> Range r'"
+  shows "children (r \<union> r') x = children r x"
+  using assms
+  by (auto simp:children_def)
+
 end
\ No newline at end of file