(* Title: HOL/MicroJava/BV/Kildall.thy
ID: $Id$
Author: Tobias Nipkow, Gerwin Klein
Copyright 2000 TUM
Kildall's algorithm
*)
header {* \isaheader{Kildall's Algorithm}\label{sec:Kildall} *}
theory Kildall = SemilatAlg + While_Combinator:
consts
iter :: "'s binop \<Rightarrow> 's step_type \<Rightarrow>
's list \<Rightarrow> nat set \<Rightarrow> 's list \<times> nat set"
propa :: "'s binop \<Rightarrow> (nat \<times> 's) list \<Rightarrow> 's list \<Rightarrow> nat set \<Rightarrow> 's list * nat set"
primrec
"propa f [] ss w = (ss,w)"
"propa f (q'#qs) ss w = (let (q,t) = q';
u = t +_f ss!q;
w' = (if u = ss!q then w else insert q w)
in propa f qs (ss[q := u]) w')"
defs iter_def:
"iter f step ss w ==
while (%(ss,w). w \<noteq> {})
(%(ss,w). let p = SOME p. p \<in> w
in propa f (step p (ss!p)) ss (w-{p}))
(ss,w)"
constdefs
unstables :: "'s ord \<Rightarrow> 's step_type \<Rightarrow> 's list \<Rightarrow> nat set"
"unstables r step ss == {p. p < size ss \<and> \<not>stable r step ss p}"
kildall :: "'s ord \<Rightarrow> 's binop \<Rightarrow> 's step_type \<Rightarrow> 's list \<Rightarrow> 's list"
"kildall r f step ss == fst(iter f step ss (unstables r step ss))"
consts merges :: "'s binop \<Rightarrow> (nat \<times> 's) list \<Rightarrow> 's list \<Rightarrow> 's list"
primrec
"merges f [] ss = ss"
"merges f (p'#ps) ss = (let (p,s) = p' in merges f ps (ss[p := s +_f ss!p]))"
lemmas [simp] = Let_def le_iff_plus_unchanged [symmetric]
lemma nth_merges:
"\<And>ss. \<lbrakk> semilat (A, r, f); p < length ss; ss \<in> list n A;
\<forall>(p,t)\<in>set ps. p<n \<and> t\<in>A \<rbrakk> \<Longrightarrow>
(merges f ps ss)!p = map snd [(p',t') \<in> ps. p'=p] ++_f ss!p"
(is "\<And>ss. _ \<Longrightarrow> _ \<Longrightarrow> _ \<Longrightarrow> ?steptype ps \<Longrightarrow> ?P ss ps")
proof (induct ps)
show "\<And>ss. ?P ss []" by simp
fix ss p' ps'
assume sl: "semilat (A, r, f)"
assume ss: "ss \<in> list n A"
assume l: "p < length ss"
assume "?steptype (p'#ps')"
then obtain a b where
p': "p'=(a,b)" and ab: "a<n" "b\<in>A" and "?steptype ps'"
by (cases p', auto)
assume "\<And>ss. semilat (A,r,f) \<Longrightarrow> p < length ss \<Longrightarrow> ss \<in> list n A \<Longrightarrow> ?steptype ps' \<Longrightarrow> ?P ss ps'"
hence IH: "\<And>ss. ss \<in> list n A \<Longrightarrow> p < length ss \<Longrightarrow> ?P ss ps'" .
from sl ss ab
have "ss[a := b +_f ss!a] \<in> list n A" by (simp add: closedD)
moreover
from calculation
have "p < length (ss[a := b +_f ss!a])" by simp
ultimately
have "?P (ss[a := b +_f ss!a]) ps'" by (rule IH)
with p' l
show "?P ss (p'#ps')" by simp
qed
(** merges **)
lemma length_merges [rule_format, simp]:
"\<forall>ss. size(merges f ps ss) = size ss"
by (induct_tac ps, auto)
lemma merges_preserves_type_lemma:
"semilat(A,r,f) \<Longrightarrow>
\<forall>xs. xs \<in> list n A \<longrightarrow> (\<forall>(p,x) \<in> set ps. p<n \<and> x\<in>A)
\<longrightarrow> merges f ps xs \<in> list n A"
apply (frule semilatDclosedI)
apply (unfold closed_def)
apply (induct_tac ps)
apply simp
apply clarsimp
done
lemma merges_preserves_type [simp]:
"\<lbrakk> semilat(A,r,f); xs \<in> list n A; \<forall>(p,x) \<in> set ps. p<n \<and> x\<in>A \<rbrakk>
\<Longrightarrow> merges f ps xs \<in> list n A"
by (simp add: merges_preserves_type_lemma)
lemma merges_incr_lemma:
"semilat(A,r,f) \<Longrightarrow>
\<forall>xs. xs \<in> list n A \<longrightarrow> (\<forall>(p,x)\<in>set ps. p<size xs \<and> x \<in> A) \<longrightarrow> xs <=[r] merges f ps xs"
apply (induct_tac ps)
apply simp
apply simp
apply clarify
apply (rule order_trans)
apply simp
apply (erule list_update_incr)
apply assumption
apply simp
apply simp
apply (blast intro!: listE_set intro: closedD listE_length [THEN nth_in])
done
lemma merges_incr:
"\<lbrakk> semilat(A,r,f); xs \<in> list n A; \<forall>(p,x)\<in>set ps. p<size xs \<and> x \<in> A \<rbrakk>
\<Longrightarrow> xs <=[r] merges f ps xs"
by (simp add: merges_incr_lemma)
lemma merges_same_conv [rule_format]:
"semilat(A,r,f) \<Longrightarrow>
(\<forall>xs. xs \<in> list n A \<longrightarrow> (\<forall>(p,x)\<in>set ps. p<size xs \<and> x\<in>A) \<longrightarrow>
(merges f ps xs = xs) = (\<forall>(p,x)\<in>set ps. x <=_r xs!p))"
apply (induct_tac ps)
apply simp
apply clarsimp
apply (rename_tac p x ps xs)
apply (rule iffI)
apply (rule context_conjI)
apply (subgoal_tac "xs[p := x +_f xs!p] <=[r] xs")
apply (force dest!: le_listD simp add: nth_list_update)
apply (erule subst, rule merges_incr)
apply assumption
apply (blast intro!: listE_set intro: closedD listE_length [THEN nth_in])
apply clarify
apply (rule conjI)
apply simp
apply (blast dest: boundedD)
apply blast
apply clarify
apply (rotate_tac -2)
apply (erule allE)
apply (erule impE)
apply assumption
apply (erule impE)
apply assumption
apply (drule bspec)
apply assumption
apply (simp add: le_iff_plus_unchanged [THEN iffD1] list_update_same_conv [THEN iffD2])
apply blast
apply clarify
apply (simp add: le_iff_plus_unchanged [THEN iffD1] list_update_same_conv [THEN iffD2])
done
lemma list_update_le_listI [rule_format]:
"set xs <= A \<longrightarrow> set ys <= A \<longrightarrow> xs <=[r] ys \<longrightarrow> p < size xs \<longrightarrow>
x <=_r ys!p \<longrightarrow> semilat(A,r,f) \<longrightarrow> x\<in>A \<longrightarrow>
xs[p := x +_f xs!p] <=[r] ys"
apply (unfold Listn.le_def lesub_def semilat_def)
apply (simp add: list_all2_conv_all_nth nth_list_update)
done
lemma merges_pres_le_ub:
"\<lbrakk> semilat(A,r,f); set ts <= A; set ss <= A;
\<forall>(p,t)\<in>set ps. t <=_r ts!p \<and> t \<in> A \<and> p < size ts;
ss <=[r] ts \<rbrakk>
\<Longrightarrow> merges f ps ss <=[r] ts"
proof -
{ fix A r f t ts ps
have
"\<And>qs. \<lbrakk> semilat(A,r,f); set ts <= A;
\<forall>(p,t)\<in>set ps. t <=_r ts!p \<and> t \<in> A \<and> p < size ts \<rbrakk> \<Longrightarrow>
set qs <= set ps \<longrightarrow>
(\<forall>ss. set ss <= A \<longrightarrow> ss <=[r] ts \<longrightarrow> merges f qs ss <=[r] ts)"
apply (induct_tac qs)
apply simp
apply (simp (no_asm_simp))
apply clarify
apply (rotate_tac -2)
apply simp
apply (erule allE, erule impE, erule_tac [2] mp)
apply (drule bspec, assumption)
apply (simp add: closedD)
apply (drule bspec, assumption)
apply (simp add: list_update_le_listI)
done
} note this [dest]
case rule_context
thus ?thesis by blast
qed
(** propa **)
lemma decomp_propa:
"\<And>ss w. (\<forall>(q,t)\<in>set qs. q < size ss) \<Longrightarrow>
propa f qs ss w =
(merges f qs ss, {q. \<exists>t. (q,t)\<in>set qs \<and> t +_f ss!q \<noteq> ss!q} Un w)"
apply (induct qs)
apply simp
apply (simp (no_asm))
apply clarify
apply simp
apply (rule conjI)
apply (simp add: nth_list_update)
apply blast
apply (simp add: nth_list_update)
apply blast
done
(** iter **)
lemma stable_pres_lemma:
"\<lbrakk> semilat (A,r,f); pres_type step n A; bounded step n;
ss \<in> list n A; p \<in> w; \<forall>q\<in>w. q < n;
\<forall>q. q < n \<longrightarrow> q \<notin> w \<longrightarrow> stable r step ss q; q < n;
\<forall>s'. (q,s') \<in> set (step p (ss ! p)) \<longrightarrow> s' +_f ss ! q = ss ! q;
q \<notin> w \<or> q = p \<rbrakk>
\<Longrightarrow> stable r step (merges f (step p (ss!p)) ss) q"
apply (unfold stable_def)
apply (subgoal_tac "\<forall>s'. (q,s') \<in> set (step p (ss!p)) \<longrightarrow> s' : A")
prefer 2
apply clarify
apply (erule pres_typeD)
prefer 3 apply assumption
apply (rule listE_nth_in)
apply assumption
apply simp
apply simp
apply simp
apply clarify
apply (subst nth_merges)
apply assumption
apply simp
apply (blast dest: boundedD)
apply assumption
apply clarify
apply (rule conjI)
apply (blast dest: boundedD)
apply (erule pres_typeD)
prefer 3 apply assumption
apply simp
apply simp
apply (frule nth_merges [of _ _ _ q _ _ "step p (ss!p)"]) (* fixme: why does method subst not work?? *)
prefer 2 apply assumption
apply simp
apply clarify
apply (rule conjI)
apply (blast dest: boundedD)
apply (erule pres_typeD)
prefer 3 apply assumption
apply simp
apply simp
apply (drule_tac P = "\<lambda>x. (a, b) \<in> set (step q x)" in subst)
apply assumption
apply (simp add: plusplus_empty)
apply (cases "q \<in> w")
apply simp
apply (rule ub1')
apply assumption
apply clarify
apply (rule pres_typeD)
apply assumption
prefer 3 apply assumption
apply (blast intro: listE_nth_in dest: boundedD)
apply (blast intro: pres_typeD dest: boundedD)
apply (blast intro: listE_nth_in dest: boundedD)
apply assumption
apply simp
apply (erule allE, erule impE, assumption, erule impE, assumption)
apply (rule order_trans)
apply simp
defer
apply (rule ub2)
apply assumption
apply simp
apply clarify
apply simp
apply (rule pres_typeD)
apply assumption
prefer 3 apply assumption
apply (blast intro: listE_nth_in dest: boundedD)
apply (blast intro: pres_typeD dest: boundedD)
apply (blast intro: listE_nth_in dest: boundedD)
apply blast
done
lemma merges_bounded_lemma:
"\<lbrakk> semilat (A,r,f); mono r step n A; bounded step n;
\<forall>(p',s') \<in> set (step p (ss!p)). s' \<in> A; ss \<in> list n A; ts \<in> list n A; p < n;
ss <=[r] ts; \<forall>p. p < n \<longrightarrow> stable r step ts p \<rbrakk>
\<Longrightarrow> merges f (step p (ss!p)) ss <=[r] ts"
apply (unfold stable_def)
apply (rule merges_pres_le_ub)
apply assumption
apply simp
apply simp
prefer 2 apply assumption
apply clarsimp
apply (drule boundedD, assumption+)
apply (erule allE, erule impE, assumption)
apply (drule bspec, assumption)
apply simp
apply (drule monoD [of _ _ _ _ p "ss!p" "ts!p"])
apply assumption
apply simp
apply (simp add: le_listD)
apply (drule lesub_step_typeD, assumption)
apply clarify
apply (drule bspec, assumption)
apply simp
apply (blast intro: order_trans)
done
lemma termination_lemma:
"\<lbrakk> semilat(A,r,f); ss \<in> list n A; \<forall>(q,t)\<in>set qs. q<n \<and> t\<in>A; p\<in>w \<rbrakk> \<Longrightarrow>
ss <[r] merges f qs ss \<or>
merges f qs ss = ss \<and> {q. \<exists>t. (q,t)\<in>set qs \<and> t +_f ss!q \<noteq> ss!q} Un (w-{p}) < w"
apply (unfold lesssub_def)
apply (simp (no_asm_simp) add: merges_incr)
apply (rule impI)
apply (rule merges_same_conv [THEN iffD1, elim_format])
apply assumption+
defer
apply (rule sym, assumption)
defer apply simp
apply (subgoal_tac "\<forall>q t. \<not>((q, t) \<in> set qs \<and> t +_f ss ! q \<noteq> ss ! q)")
apply (blast intro!: psubsetI elim: equalityE)
apply clarsimp
apply (drule bspec, assumption)
apply (drule bspec, assumption)
apply clarsimp
done
lemma iter_properties[rule_format]:
"\<lbrakk> semilat(A,r,f); acc r ; pres_type step n A; mono r step n A;
bounded step n; \<forall>p\<in>w0. p < n; ss0 \<in> list n A;
\<forall>p<n. p \<notin> w0 \<longrightarrow> stable r step ss0 p \<rbrakk> \<Longrightarrow>
iter f step ss0 w0 = (ss',w')
\<longrightarrow>
ss' \<in> list n A \<and> stables r step ss' \<and> ss0 <=[r] ss' \<and>
(\<forall>ts\<in>list n A. ss0 <=[r] ts \<and> stables r step ts \<longrightarrow> ss' <=[r] ts)"
apply (unfold iter_def stables_def)
apply (rule_tac P = "%(ss,w).
ss \<in> list n A \<and> (\<forall>p<n. p \<notin> w \<longrightarrow> stable r step ss p) \<and> ss0 <=[r] ss \<and>
(\<forall>ts\<in>list n A. ss0 <=[r] ts \<and> stables r step ts \<longrightarrow> ss <=[r] ts) \<and>
(\<forall>p\<in>w. p < n)" and
r = "{(ss',ss) . ss <[r] ss'} <*lex*> finite_psubset"
in while_rule)
-- "Invariant holds initially:"
apply (simp add:stables_def)
-- "Invariant is preserved:"
apply(simp add: stables_def split_paired_all)
apply(rename_tac ss w)
apply(subgoal_tac "(SOME p. p \<in> w) \<in> w")
prefer 2; apply (fast intro: someI)
apply(subgoal_tac "\<forall>(q,t) \<in> set (step (SOME p. p \<in> w) (ss ! (SOME p. p \<in> w))). q < length ss \<and> t \<in> A")
prefer 2
apply clarify
apply (rule conjI)
apply(clarsimp, blast dest!: boundedD)
apply (erule pres_typeD)
prefer 3
apply assumption
apply (erule listE_nth_in)
apply blast
apply blast
apply (subst decomp_propa)
apply blast
apply simp
apply (rule conjI)
apply (erule merges_preserves_type)
apply blast
apply clarify
apply (rule conjI)
apply(clarsimp, blast dest!: boundedD)
apply (erule pres_typeD)
prefer 3
apply assumption
apply (erule listE_nth_in)
apply blast
apply blast
apply (rule conjI)
apply clarify
apply (blast intro!: stable_pres_lemma)
apply (rule conjI)
apply (blast intro!: merges_incr intro: le_list_trans)
apply (rule conjI)
apply clarsimp
apply (blast intro!: merges_bounded_lemma)
apply (blast dest!: boundedD)
-- "Postcondition holds upon termination:"
apply(clarsimp simp add: stables_def split_paired_all)
-- "Well-foundedness of the termination relation:"
apply (rule wf_lex_prod)
apply (drule (1) semilatDorderI [THEN acc_le_listI])
apply (simp only: acc_def lesssub_def)
apply (rule wf_finite_psubset)
-- "Loop decreases along termination relation:"
apply(simp add: stables_def split_paired_all)
apply(rename_tac ss w)
apply(subgoal_tac "(SOME p. p \<in> w) \<in> w")
prefer 2; apply (fast intro: someI)
apply(subgoal_tac "\<forall>(q,t) \<in> set (step (SOME p. p \<in> w) (ss ! (SOME p. p \<in> w))). q < length ss \<and> t \<in> A")
prefer 2
apply clarify
apply (rule conjI)
apply(clarsimp, blast dest!: boundedD)
apply (erule pres_typeD)
prefer 3
apply assumption
apply (erule listE_nth_in)
apply blast
apply blast
apply (subst decomp_propa)
apply blast
apply clarify
apply (simp del: listE_length
add: lex_prod_def finite_psubset_def
bounded_nat_set_is_finite)
apply (rule termination_lemma)
apply assumption+
defer
apply assumption
apply clarsimp
apply (blast dest!: boundedD)
done
lemma kildall_properties:
"\<lbrakk> semilat(A,r,f); acc r; pres_type step n A; mono r step n A;
bounded step n; ss0 \<in> list n A \<rbrakk> \<Longrightarrow>
kildall r f step ss0 \<in> list n A \<and>
stables r step (kildall r f step ss0) \<and>
ss0 <=[r] kildall r f step ss0 \<and>
(\<forall>ts\<in>list n A. ss0 <=[r] ts \<and> stables r step ts \<longrightarrow>
kildall r f step ss0 <=[r] ts)"
apply (unfold kildall_def)
apply(case_tac "iter f step ss0 (unstables r step ss0)")
apply(simp)
apply (rule iter_properties)
apply (simp_all add: unstables_def stable_def)
done
lemma is_bcv_kildall:
"\<lbrakk> semilat(A,r,f); acc r; top r T;
pres_type step n A; bounded step n;
mono r step n A \<rbrakk>
\<Longrightarrow> is_bcv r T step n A (kildall r f step)"
apply(unfold is_bcv_def wt_step_def)
apply(insert kildall_properties[of A])
apply(simp add:stables_def)
apply clarify
apply(subgoal_tac "kildall r f step ss \<in> list n A")
prefer 2 apply (simp(no_asm_simp))
apply (rule iffI)
apply (rule_tac x = "kildall r f step ss" in bexI)
apply (rule conjI)
apply blast
apply (simp (no_asm_simp))
apply assumption
apply clarify
apply(subgoal_tac "kildall r f step ss!p <=_r ts!p")
apply simp
apply (blast intro!: le_listD less_lengthI)
done
end