diff --git a/packages/CLPBN/clpbn.yap b/packages/CLPBN/clpbn.yap
index 55458e9ff..2decbd55a 100644
--- a/packages/CLPBN/clpbn.yap
+++ b/packages/CLPBN/clpbn.yap
@@ -238,11 +238,19 @@ clpbn_marginalise(V, Dist) :-
 % called by top-level
 % or by call_residue/2
 %
-project_attributes(GVars, _AVars0) :-
+project_attributes(GVars0, _AVars0) :-
 	use_parfactors(on),
 	clpbn_flag(solver, Solver), Solver \= fove, !,
-	generate_network(GVars, GKeys, Keys, Factors, Evidence),
-	call_ground_solver(Solver, GVars, GKeys, Keys, Factors, Evidence).
+	generate_network(GVars0, GKeys, Keys, Factors, Evidence),
+	b_setval(clpbn_query_variables, f(GVars0,Evidence)),
+	simplify_query(GVars0, GVars),
+	( GKeys = [] 
+        ->
+	  GVars0 = [V|_],
+	  clpbn_display:put_atts(V, [posterior([],[],[],[])])
+	;
+	  call_ground_solver(Solver, GVars, GKeys, Keys, Factors, Evidence)
+        ).
 project_attributes(GVars, AVars) :-
 	suppress_attribute_display(false),
 	AVars = [_|_],
@@ -262,6 +270,20 @@ project_attributes(GVars, AVars) :-
 	).
 project_attributes(_, _).
 
+%
+% check for query variables with evidence
+%
+simplify_query([V|GVars0], GVars) :-
+	get_atts(V, [evidence(_)]), !,
+	simplify_query(GVars0, GVars).
+simplify_query([V|GVars0], GVars) :-
+	get_atts(V, [key(K)]),
+	pfl:evidence(K, _), !,
+	simplify_query(GVars0, GVars).
+simplify_query([V|GVars0], [V|GVars]) :-
+	simplify_query(GVars0, GVars).
+simplify_query([], []).
+
 match([], _Keys).
 match([V|GVars], Keys) :-
 	clpbn:get_atts(V,[key(GKey)]),
@@ -279,13 +301,7 @@ get_clpbn_vars([V|GVars],[V|CLPBNGVars]) :-
 	get_clpbn_vars(GVars,CLPBNGVars).
 get_clpbn_vars([_|GVars],CLPBNGVars) :-
 	get_clpbn_vars(GVars,CLPBNGVars).
-
 get_clpbn_vars([],[]).
-get_clpbn_vars([V|GVars],[V|CLPBNGVars]) :-
-	get_atts(V, [key(_)]), !,
-	get_clpbn_vars(GVars,CLPBNGVars).
-get_clpbn_vars([_|GVars],CLPBNGVars) :-
-	get_clpbn_vars(GVars,CLPBNGVars).
 
 simplify_query_vars(LVs0, LVs) :-
 	sort(LVs0,LVs1),
@@ -305,6 +321,7 @@ get_rid_of_ev_vars([V|LVs0],[V|LVs]) :-
 
 
 % do nothing if we don't have query variables to compute.
+write_out(_, [], _, _) :- !.
 write_out(graphs, _, AVars, _) :-
 	clpbn2graph(AVars).
 write_out(ve, GVars, AVars, DiffVars) :-
@@ -651,21 +668,14 @@ variabilise_last([Arg], Arg, [V], V).
 variabilise_last([Arg1,Arg2|Args], Arg, Arg1.NArgs, V) :-
 	variabilise_last(Arg2.Args, Arg, NArgs, V).
 
-match_probability([], Goal, C, V, Prob) :-
-    /* there is evidence, so values are nil and V is bound */
-    nonvar(V), !,
-    goal_to_key(Goal, Skolem),
-    pfl:skolem(Skolem, Domain),
-    member(C, Domain),
-    ( C == V -> Prob = 1.0 ; Prob = 0.0 ).
 match_probability(VPs, Goal, C, V, Prob) :-
     match_probabilities(VPs, Goal, C, V, Prob).
 
 match_probabilities([p(V0=C)=Prob|_], _, C, V, Prob) :-
     V0 == V,
     !.
-match_probabilies([_|Probs], G, C, V, Prob) :-
-    match_probability(Probs, G, C, V, Prob).
+match_probabilities([_|Probs], G, C, V, Prob) :-
+    match_probabilities(Probs, G, C, V, Prob).
 
 goal_to_key(_:Goal, Skolem) :-
     goal_to_key(Goal, Skolem).
diff --git a/packages/CLPBN/clpbn/display.yap b/packages/CLPBN/clpbn/display.yap
index 0e96a2e7b..b8c9575c6 100644
--- a/packages/CLPBN/clpbn/display.yap
+++ b/packages/CLPBN/clpbn/display.yap
@@ -10,6 +10,8 @@
 
 :- use_module(library(clpbn), [use_parfactors/1]).
 
+:- use_module(library(maplist)).
+
 :- attribute posterior/4.
 
 
@@ -21,15 +23,42 @@ attribute_goal(V, G) :-
 	get_atts(V, [posterior(Vs,Vals,Ps,AllDiffs)]),
 	massage_out(Vs, Vals, Ps, G, AllDiffs, V).
 
-massage_out([], Ev, _, V=Ev, _, V) :- !.
-massage_out(Vs, [D], [P], p(CEqs)=P, AllDiffs, _) :- !,
+massage_out([], _Ev, _, Out, _, _V) :- !,
+	out_query_evidence(Out).
+massage_out(Vs, [D], [P], O, AllDiffs, _) :- !,
 	gen_eqs(Vs,D,Eqs),
-	add_alldiffs(AllDiffs,Eqs,CEqs).
+	add_alldiffs(AllDiffs,Eqs,CEqs),
+	out_query_evidence(Out),
+	( Out = true -> O = (p(CEqs)=P) ; O = (p(CEqs)=P, Out) ).
 massage_out(Vs, [D|Ds], [P|Ps], (p(CEqs)=P,G) , AllDiffs, V) :-
 	gen_eqs(Vs,D,Eqs),
 	add_alldiffs(AllDiffs,Eqs,CEqs),
 	massage_out(Vs, Ds, Ps, G, AllDiffs, V).
 
+out_query_evidence(Out) :-
+	catch(b_getval(clpbn_query_variables, f(QVs,Evidence)), _, fail), !,
+	foldl( process_qv(Evidence), QVs, [], OL),
+	list_to_conj(OL, Out).
+out_query_evidence(true).
+
+process_qv(Evidence, V, L0, LF) :-
+	clpbn:get_atts(V,[key(K)]),
+	member(K=Ev, Evidence), !,
+	pfl:skolem(K,Dom),
+	foldl2( add_goal(V,Ev), Dom, 0, _, L0, LF ).
+process_qv(_Ev, _V, L, L).
+
+list_to_conj([], true).
+list_to_conj([O], O) :- !.
+list_to_conj([O|OL], (O,Out)) :-
+	list_to_conj(OL, Out).
+
+add_goal(V, Ev, DVal, Ev, I, L, [(p(V=DVal) = 1.0)|L]) :- !,
+	I is Ev+1.
+add_goal(V, _Ev, DVal, I0, I, L, [(p(V=DVal) = 0.0)|L]) :- !,
+	I is I0+1.
+
+
 gen_eqs([V], [D], (V=D)) :- !.
 gen_eqs([V], D, (V=D)) :- !.
 gen_eqs([V|Vs], [D|Ds], ((V=D),Eqs)) :-