d02bc3de81
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@2143 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
219 lines
6.8 KiB
Prolog
219 lines
6.8 KiB
Prolog
/***********************************
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Variable Elimination in Prolog
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How to do it
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Three steps:
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build the graph:
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- for all variables, find out
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all tables they connect to;
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multiply their size
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order by size
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*********************************/
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:- module(vel, [vel/3,
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check_if_vel_done/1]).
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:- attribute size/1, all_diffs/1.
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:- use_module(library(ordsets), [ord_union/3]).
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:- use_module(library('clpbn/xbif'), [clpbn2xbif/3]).
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:- use_module(library('clpbn/graphviz'), [clpbn2gviz/4]).
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:- use_module(library('clpbn/dists'),
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[
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get_dist_domain_size/2,
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get_dist_matrix/5]).
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:- use_module(library('clpbn/utils'), [
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clpbn_not_var_member/2,
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check_for_hidden_vars/3]).
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:- use_module(library('clpbn/display'), [
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clpbn_bind_vals/3]).
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:- use_module(library('clpbn/matrix_cpt_utils'),
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[project_from_CPT/3,
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reorder_CPT/5,
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multiply_CPTs/4,
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normalise_CPT/2,
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list_from_CPT/2]).
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:- use_module(library(lists),
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[
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append/3
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]).
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check_if_vel_done(Var) :-
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get_atts(Var, [size(_)]), !.
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%
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% implementation of the well known variable elimination algorithm
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%
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vel([],_,_) :- !.
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vel(LVs,Vs0,AllDiffs) :-
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check_for_hidden_vars(Vs0, Vs0, Vs1),
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sort(Vs1,Vs),
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% LVi will have a list of CLPBN variables
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% Tables0 will have the full data on each variable
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find_all_clpbn_vars(Vs, LV0, LVi, Tables0),
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% construct the graph
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find_all_table_deps(Tables0, LV0),
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(clpbn:output(xbif(XBifStream)) -> clpbn2xbif(XBifStream,vel,Vs) ; true),
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(clpbn:output(gviz(XBifStream)) -> clpbn2gviz(XBifStream,vel,Vs,LVs) ; true),
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% variable elimination proper
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process(LVi, LVs, tab(Dist,_,_)),
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% move from potentials back to probabilities
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normalise_CPT(Dist,Ps),
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% from array to list
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list_from_CPT(Ps, LPs),
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% bind Probs back to variables so that they can be output.
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clpbn_bind_vals(LVs,LPs,AllDiffs).
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%
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% just get a list of variables plus associated tables
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%
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find_all_clpbn_vars([], [], [], []) :- !.
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find_all_clpbn_vars([V|Vs], [Var|LV], ProcessedVars, [table(I,Table,Parents,Sizes)|Tables]) :-
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var_with_deps(V, Table, Parents, Sizes, Ev, Vals), !,
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% variables with evidence should not be processed.
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(var(Ev) ->
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Var = var(V,I,Sz,Vals,Parents,Ev,_,_),
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vel_get_dist_size(V,Sz),
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ProcessedVars = [Var|ProcessedVars0]
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;
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ProcessedVars = ProcessedVars0
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),
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find_all_clpbn_vars(Vs, LV, ProcessedVars0, Tables).
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var_with_deps(V, Table, Deps, Sizes, Ev, Vals) :-
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clpbn:get_atts(V, [dist(Id,Parents)]),
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get_dist_matrix(Id,Parents,_,Vals,TAB0),
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( clpbn:get_atts(V, [evidence(Ev)]) -> true ; true),
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% set CPT in canonical form
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reorder_CPT([V|Parents],TAB0,Deps0,TAB1,Sizes1),
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% remove evidence.
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simplify_evidence(Deps0, TAB1, Deps0, Sizes1, Table, Deps, Sizes).
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find_all_table_deps(Tables0, LV) :-
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find_dep_graph(Tables0, DepGraph0),
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sort(DepGraph0, DepGraph),
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add_table_deps_to_variables(LV, DepGraph).
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find_dep_graph([], []).
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find_dep_graph([table(I,Tab,Deps,Sizes)|Tables], DepGraph) :-
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add_table_deps(Deps, I, Deps, Tab, Sizes, DepGraph0, DepGraph),
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find_dep_graph(Tables, DepGraph0).
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add_table_deps([], _, _, _, _, DepGraph, DepGraph).
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add_table_deps([V|Deps], I, Deps0, Table, Sizes, DepGraph0, [V-tab(Table,Deps0,Sizes)|DepGraph]) :-
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add_table_deps(Deps, I, Deps0, Table, Sizes, DepGraph0, DepGraph).
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add_table_deps_to_variables([], []).
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add_table_deps_to_variables([var(V,_,_,_,_,_,Deps,K)|LV], DepGraph) :-
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steal_deps_for_variable(DepGraph, V, NDepGraph, Deps),
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compute_size(Deps,[],K),
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% ( clpbn:get_atts(V,[key(Key)]) -> format('~w:~w~n',[Key,K]) ; true),
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add_table_deps_to_variables(LV, NDepGraph).
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steal_deps_for_variable([V-Info|DepGraph], V0, NDepGraph, [Info|Deps]) :-
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V == V0, !,
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steal_deps_for_variable(DepGraph, V0, NDepGraph, Deps).
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steal_deps_for_variable(DepGraph, _, DepGraph, []).
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compute_size([],Vs,K) :-
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% use sizes now
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% length(Vs,K).
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multiply_sizes(Vs,1,K).
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compute_size([tab(_,Vs,_)|Tabs],Vs0,K) :-
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ord_union(Vs,Vs0,VsI),
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compute_size(Tabs,VsI,K).
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multiply_sizes([],K,K).
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multiply_sizes([V|Vs],K0,K) :-
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vel_get_dist_size(V, Sz),
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KI is K0*Sz,
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multiply_sizes(Vs,KI,K).
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process(LV0, InputVs, Out) :-
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find_best(LV0, V0, -1, V, WorkTables, LVI, InputVs),
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V \== V0, !,
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% format('1 ~w: ~w~n',[V,WorkTables]),
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multiply_tables(WorkTables, tab(Tab0,Deps0,_)),
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reorder_CPT(Deps0,Tab0,Deps,Tab,Sizes),
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Table = tab(Tab,Deps,Sizes),
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% format('2 ~w: ~w~n',[V,Table]),
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project_from_CPT(V,Table,NewTable),
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% format('3 ~w: ~w~n',[V,NewTable]),
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include(LVI,NewTable,V,LV2),
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process(LV2, InputVs, Out).
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process(LV0, _, Out) :-
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fetch_tables(LV0, WorkTables),
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multiply_tables(WorkTables, Out).
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find_best([], V, _TF, V, _, [], _).
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%:-
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% clpbn:get_atts(V,[key(K)]), write(chosen:K:TF), nl.
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% root_with_single_child
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%find_best([var(V,I,_,_,[],Ev,[Dep],K)|LV], _, _, V, [Dep], LVF, Inputs) :- !.
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find_best([var(V,I,Sz,Vals,Parents,Ev,Deps,K)|LV], _, Threshold, VF, NWorktables, LVF, Inputs) :-
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( K < Threshold ; Threshold < 0),
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clpbn_not_var_member(Inputs, V), !,
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find_best(LV, V, K, VF, WorkTables,LV0, Inputs),
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(V == VF ->
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LVF = LV0, Deps = NWorktables
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;
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LVF = [var(V,I,Sz,Vals,Parents,Ev,Deps,K)|LV0], WorkTables = NWorktables
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).
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find_best([V|LV], V0, Threshold, VF, WorkTables, [V|LVF], Inputs) :-
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find_best(LV, V0, Threshold, VF, WorkTables, LVF, Inputs).
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multiply_tables([Table], Table) :- !.
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multiply_tables([TAB1, TAB2| Tables], Out) :-
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multiply_CPTs(TAB1, TAB2, TAB, _),
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multiply_tables([TAB| Tables], Out).
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simplify_evidence([], Table, Deps, Sizes, Table, Deps, Sizes).
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simplify_evidence([V|VDeps], Table0, Deps0, Sizes0, Table, Deps, Sizes) :-
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clpbn:get_atts(V, [evidence(_)]), !,
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project_from_CPT(V,tab(Table0,Deps0,Sizes0),tab(NewTable,Deps1,Sizes1)),
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simplify_evidence(VDeps, NewTable, Deps1, Sizes1, Table, Deps, Sizes).
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simplify_evidence([_|VDeps], Table0, Deps0, Sizes0, Table, Deps, Sizes) :-
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simplify_evidence(VDeps, Table0, Deps0, Sizes0, Table, Deps, Sizes).
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fetch_tables([], []).
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fetch_tables([var(_,_,_,_,_,_,Deps,_)|LV0], Tables) :-
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append(Deps,Tables0,Tables),
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fetch_tables(LV0, Tables0).
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%
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include([],_,_,[]).
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include([var(V,P,VSz,D,Parents,Ev,Tabs,Est)|LV],tab(T,Vs,Sz),V1,[var(V,P,VSz,D,Parents,Ev,Tabs,Est)|NLV]) :-
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clpbn_not_var_member(Vs,V), !,
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include(LV,tab(T,Vs,Sz),V1,NLV).
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include([var(V,P,VSz,D,Parents,Ev,Tabs,_)|LV],Table,NV,[var(V,P,VSz,D,Parents,Ev,NTabs,NEst)|NLV]) :-
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update_tables(Tabs,NTabs,Table,NV),
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compute_size(NTabs, [], NEst),
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include(LV,Table,NV,NLV).
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update_tables([],[Table],Table,_).
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update_tables([tab(Tab0,Vs,Sz)|Tabs],[tab(Tab0,Vs,Sz)|NTabs],Table,V) :-
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clpbn_not_var_member(Vs,V), !,
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update_tables(Tabs,NTabs,Table,V).
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update_tables([_|Tabs],NTabs,Table,V) :-
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update_tables(Tabs,NTabs,Table,V).
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vel_get_dist_size(V,Sz) :-
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get_atts(V, [size(Sz)]), !.
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vel_get_dist_size(V,Sz) :-
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clpbn:get_atts(V,dist(Id,_)), !,
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get_dist_domain_size(Id,Sz),
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put_atts(V, [size(Sz)]).
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