diff --git a/C/arrays.c b/C/arrays.c
index f0fa0fb11..4fbcd3da7 100644
--- a/C/arrays.c
+++ b/C/arrays.c
@@ -1066,6 +1066,7 @@ static Int create_static_array(USES_REGS1) {
   Int size;
   static_array_types props;
   void *address = NULL;
+  
 
   if (IsVarTerm(ti)) {
     Yap_Error(INSTANTIATION_ERROR, ti, "create static array");
diff --git a/C/c_interface.c b/C/c_interface.c
index f2c7425cb..82da72fdf 100755
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -421,8 +421,25 @@ X_API void *YAP_BlobOfTerm(Term t) {
 
   if (IsVarTerm(t))
     return NULL;
-  if (!IsBigIntTerm(t))
+  if (!IsBigIntTerm(t)) {
+    if (IsAtomTerm(t)) {
+         AtomEntry *ae = RepAtom(AtomOfTerm(t));
+    StaticArrayEntry *pp;
+
+    READ_LOCK(ae->ARWLock);
+    pp = RepStaticArrayProp(ae->PropsOfAE);
+    while (!EndOfPAEntr(pp) && pp->KindOfPE != ArrayProperty)
+      pp = RepStaticArrayProp(pp->NextOfPE);
+    if (EndOfPAEntr(pp) || pp->ValueOfVE.ints == NULL) {
+      READ_UNLOCK(ae->ARWLock);
+      return NULL;
+    } else {
+      READ_UNLOCK(ae->ARWLock);
+      return pp->ValueOfVE.ints;
+   }
+    }
     return NULL;
+  }
   src = (MP_INT *)(RepAppl(t) + 2);
   return (void *)(src + 1);
 }
diff --git a/C/cdmgr.c b/C/cdmgr.c
index c14a69ab0..f01008abf 100644
--- a/C/cdmgr.c
+++ b/C/cdmgr.c
@@ -2069,6 +2069,7 @@ static Int p_startconsult(USES_REGS1) { /* '$start_consult'(+Mode)	 */
   char *smode = RepAtom(AtomOfTerm(Deref(ARG1)))->StrOfAE;
   int mode;
 
+  setBooleanLocalPrologFlag(COMPILING_FLAG, AtomTrue);
   mode = strcmp("consult", (char *)smode);
   Yap_init_consult(mode, RepAtom(AtomOfTerm(Deref(ARG2)))->StrOfAE);
   t = MkIntTerm(LOCAL_consult_level);
@@ -2092,6 +2093,7 @@ static void end_consult(USES_REGS1) {
 /*  if (LOCAL_consult_level == 0)
     do_toggle_static_predicates_in_use(FALSE);*/
 #endif
+  setBooleanLocalPrologFlag(COMPILING_FLAG, AtomFalse);
 }
 
 void Yap_end_consult(void) {
@@ -2388,19 +2390,12 @@ static Int
  * */
 static Int new_multifile(USES_REGS1) {
   PredEntry *pe;
-  Atom at;
-  arity_t arity;
 
   pe = new_pred(Deref(ARG1), Deref(ARG2), "multifile");
   if (EndOfPAEntr(pe))
     return FALSE;
   PELOCK(30, pe);
-  arity = pe->ArityOfPE;
-  if (arity == 0)
-    at = (Atom)pe->FunctorOfPred;
-  else
-    at = NameOfFunctor(pe->FunctorOfPred);
-
+ 
   if (pe->PredFlags & MultiFileFlag) {
     UNLOCKPE(26, pe);
     return true;
@@ -2631,18 +2626,11 @@ static Int p_set_owner_file(USES_REGS1) { /* '$owner_file'(+P,M,F)	 */
 
 static Int mk_dynamic(USES_REGS1) { /* '$make_dynamic'(+P)	 */
   PredEntry *pe;
-  Atom at;
-  arity_t arity;
 
   pe = new_pred(Deref(ARG1), Deref(ARG2), "dynamic");
   if (EndOfPAEntr(pe))
     return FALSE;
   PELOCK(30, pe);
-  arity = pe->ArityOfPE;
-  if (arity == 0)
-    at = (Atom)pe->FunctorOfPred;
-  else
-    at = NameOfFunctor(pe->FunctorOfPred);
 
   if (pe->PredFlags &
       (UserCPredFlag | CArgsPredFlag | NumberDBPredFlag | AtomDBPredFlag |
@@ -2694,18 +2682,11 @@ static Int p_is_dynamic(USES_REGS1) { /* '$is_dynamic'(+P)	 */
  * */
 static Int new_meta_pred(USES_REGS1) {
   PredEntry *pe;
-  Atom at;
-  arity_t arity;
 
   pe = new_pred(Deref(ARG1), Deref(ARG2), "meta_predicate");
   if (EndOfPAEntr(pe))
     return false;
   PELOCK(30, pe);
-  arity = pe->ArityOfPE;
-  if (arity == 0)
-    at = (Atom)pe->FunctorOfPred;
-  else
-    at = NameOfFunctor(pe->FunctorOfPred);
 
   if (pe->PredFlags & MetaPredFlag) {
     UNLOCKPE(26, pe);
diff --git a/C/exec.c b/C/exec.c
index 58f9788c4..e2dcc8879 100755
--- a/C/exec.c
+++ b/C/exec.c
@@ -183,11 +183,11 @@ restart:
     if (fun == FunctorModule) {
       Term tmod = ArgOfTerm(1, t);
       if (IsVarTerm(tmod)) {
-        Yap_Error(INSTANTIATION_ERROR, t0, pname);
+        Yap_ThrowError(INSTANTIATION_ERROR, t0, pname);
         return NULL;
       }
       if (!IsAtomTerm(tmod)) {
-        Yap_Error(TYPE_ERROR_ATOM, t0, pname);
+        Yap_ThrowError(TYPE_ERROR_ATOM, t0, pname);
         return NULL;
       }
       t = ArgOfTerm(2, t);
@@ -196,7 +196,7 @@ restart:
     PredEntry *ap = RepPredProp(Yap_GetPredPropByFunc(fun, tmod));
     return ap;
   } else {
-    Yap_Error(TYPE_ERROR_CALLABLE, t0, pname);
+    Yap_ThrowError(TYPE_ERROR_CALLABLE, t0, pname);
   }
   return NULL;
 }
@@ -214,8 +214,7 @@ Term Yap_TermToIndicator(Term t, Term mod) {
     ti[0] = MkAtomTerm(AtomDot);
     ti[1] = MkIntTerm(2);
   } else {
-    ti[0] = t;
-    ti[1] = MkIntTerm(0);
+      return  t;
   }
   t = Yap_MkApplTerm(FunctorSlash, 2, ti);
   if (mod != PROLOG_MODULE && mod != USER_MODULE && mod != TermProlog) {
@@ -254,7 +253,7 @@ static bool CallError(yap_error_number err, Term t, Term mod USES_REGS) {
     if (err == TYPE_ERROR_CALLABLE) {
       t = Yap_YapStripModule(t, &mod);
     }
-    Yap_Error(err, t, "call/1");
+    Yap_ThrowError(err, t, "call/1");
     return false;
   }
 }
@@ -345,7 +344,7 @@ static PredEntry *new_pred(Term t, Term tmod, char *pname) {
 
 restart:
   if (IsVarTerm(t)) {
-    Yap_Error(INSTANTIATION_ERROR, t0, pname);
+    Yap_ThrowError(INSTANTIATION_ERROR, t0, pname);
     return NULL;
   } else if (IsAtomTerm(t)) {
     return RepPredProp(PredPropByAtom(AtomOfTerm(t), tmod));
@@ -354,17 +353,17 @@ restart:
   } else if (IsApplTerm(t)) {
     Functor fun = FunctorOfTerm(t);
     if (IsExtensionFunctor(fun)) {
-      Yap_Error(TYPE_ERROR_CALLABLE, Yap_TermToIndicator(t, tmod), pname);
+      Yap_ThrowError(TYPE_ERROR_CALLABLE, Yap_TermToIndicator(t, tmod), pname);
       return NULL;
     }
     if (fun == FunctorModule) {
       Term tmod = ArgOfTerm(1, t);
       if (IsVarTerm(tmod)) {
-        Yap_Error(INSTANTIATION_ERROR, t0, pname);
+        Yap_ThrowError(INSTANTIATION_ERROR, t0, pname);
         return NULL;
       }
       if (!IsAtomTerm(tmod)) {
-        Yap_Error(TYPE_ERROR_ATOM, t0, pname);
+        Yap_ThrowError(TYPE_ERROR_ATOM, t0, pname);
         return NULL;
       }
       t = ArgOfTerm(2, t);
@@ -601,7 +600,7 @@ static bool EnterCreepMode(Term t, Term mod USES_REGS) {
   if (Yap_get_signal(YAP_CDOVF_SIGNAL)) {
     ARG1 = t;
     if (!Yap_locked_growheap(FALSE, 0, NULL)) {
-      Yap_Error(RESOURCE_ERROR_HEAP, TermNil,
+      Yap_ThrowError(RESOURCE_ERROR_HEAP, TermNil,
                 "YAP failed to grow heap at meta-call");
     }
     if (!Yap_has_a_signal()) {
@@ -780,7 +779,7 @@ static Int execute_clause(USES_REGS1) { /* '$execute_clause'(Goal)	 */
 
 restart_exec:
   if (IsVarTerm(t)) {
-    Yap_Error(INSTANTIATION_ERROR, ARG3, "call/1");
+    Yap_ThrowError(INSTANTIATION_ERROR, ARG3, "call/1");
     return FALSE;
   } else if (IsAtomTerm(t)) {
     Atom a = AtomOfTerm(t);
@@ -852,9 +851,11 @@ static void prune_inner_computation(choiceptr parent) {
   Int oENV = LCL0 - ENV;
 
   cut_pt = B;
-  while (cut_pt->cp_b < parent) {
+  while (cut_pt && cut_pt->cp_b < parent) {
     cut_pt = cut_pt->cp_b;
   }
+  if (!cut_pt)
+    return;
 #ifdef YAPOR
   CUT_prune_to(cut_pt);
 #endif
@@ -1231,7 +1232,7 @@ static Int execute0(USES_REGS1) { /* '$execute0'(Goal,Mod)	 */
   t = Yap_YapStripModule(t, &mod);
 restart_exec:
   if (IsVarTerm(t)) {
-    Yap_Error(INSTANTIATION_ERROR, ARG3, "call/1");
+    Yap_ThrowError(INSTANTIATION_ERROR, ARG3, "call/1");
     return false;
   } else if (IsAtomTerm(t)) {
     Atom a = AtomOfTerm(t);
@@ -1285,7 +1286,7 @@ restart_exec:
 #endif
     }
   } else {
-    //Yap_Error(TYPE_ERROR_CALLABLE, t, "call/1");
+    //Yap_ThrowError(TYPE_ERROR_CALLABLE, t, "call/1");
     //return false;
     return CallMetaCall(t, mod);
   }
@@ -1306,11 +1307,11 @@ static Int creep_step(USES_REGS1) { /* '$execute_nonstop'(Goal,Mod)
   if (IsVarTerm(mod)) {
     mod = CurrentModule;
   } else if (!IsAtomTerm(mod)) {
-    Yap_Error(TYPE_ERROR_ATOM, ARG2, "call/1");
+    Yap_ThrowError(TYPE_ERROR_ATOM, ARG2, "call/1");
     return FALSE;
   }
   if (IsVarTerm(t)) {
-    Yap_Error(INSTANTIATION_ERROR, ARG1, "call/1");
+    Yap_ThrowError(INSTANTIATION_ERROR, ARG1, "call/1");
     return FALSE;
   } else if (IsAtomTerm(t)) {
     Atom a = AtomOfTerm(t);
@@ -1388,11 +1389,11 @@ static Int execute_nonstop(USES_REGS1) {
   if (IsVarTerm(mod)) {
     mod = CurrentModule;
   } else if (!IsAtomTerm(mod)) {
-    Yap_Error(TYPE_ERROR_ATOM, ARG2, "call/1");
+    Yap_ThrowError(TYPE_ERROR_ATOM, ARG2, "call/1");
     return FALSE;
   }
   if (IsVarTerm(t)) {
-    Yap_Error(INSTANTIATION_ERROR, ARG1, "call/1");
+    Yap_ThrowError(INSTANTIATION_ERROR, ARG1, "call/1");
     return FALSE;
   } else if (IsAtomTerm(t)) {
     Atom a = AtomOfTerm(t);
@@ -1425,7 +1426,7 @@ static Int execute_nonstop(USES_REGS1) {
 #endif
     }
   } else {
-    Yap_Error(TYPE_ERROR_CALLABLE, t, "call/1");
+    Yap_ThrowError(TYPE_ERROR_CALLABLE, t, "call/1");
     return FALSE;
   }
   /*	N = arity; */
@@ -1528,13 +1529,13 @@ static Int execute_10(USES_REGS1) { /* '$execute_10'(Goal)	 */
 static Int execute_depth_limit(USES_REGS1) {
   Term d = Deref(ARG2);
   if (IsVarTerm(d)) {
-    Yap_Error(INSTANTIATION_ERROR, d, "depth_bound_call/2");
+    Yap_ThrowError(INSTANTIATION_ERROR, d, "depth_bound_call/2");
     return false;
   } else if (!IsIntegerTerm(d)) {
     if (IsFloatTerm(d) && isinf(FloatOfTerm(d))) {
       DEPTH = RESET_DEPTH();
     } else {
-      Yap_Error(TYPE_ERROR_INTEGER, d, "depth_bound_call/2");
+      Yap_ThrowError(TYPE_ERROR_INTEGER, d, "depth_bound_call/2");
       return false;
     }
   } else {
@@ -1866,7 +1867,7 @@ bool Yap_execute_pred(PredEntry *ppe, CELL *pt, bool pass_ex USES_REGS) {
     }
     return false;
   } else {
-    Yap_Error(SYSTEM_ERROR_INTERNAL, TermNil, "emulator crashed");
+    Yap_ThrowError(SYSTEM_ERROR_INTERNAL, TermNil, "emulator crashed");
     return false;
   }
 }
@@ -1889,7 +1890,7 @@ bool Yap_execute_goal(Term t, int nargs, Term mod, bool pass_ex) {
     Functor f = FunctorOfTerm(t);
 
     if (IsBlobFunctor(f)) {
-      Yap_Error(TYPE_ERROR_CALLABLE, t, "call/1");
+      Yap_ThrowError(TYPE_ERROR_CALLABLE, t, "call/1");
       return false;
     }
     /* I cannot use the standard macro here because
@@ -1898,7 +1899,7 @@ bool Yap_execute_goal(Term t, int nargs, Term mod, bool pass_ex) {
     pt = RepAppl(t) + 1;
     pe = PredPropByFunc(f, mod);
   } else {
-    Yap_Error(TYPE_ERROR_CALLABLE, t, "call/1");
+    Yap_ThrowError(TYPE_ERROR_CALLABLE, t, "call/1");
     return false;
   }
   ppe = RepPredProp(pe);
@@ -1939,7 +1940,7 @@ Term Yap_RunTopGoal(Term t, bool handle_errors) {
 
   t = Yap_YapStripModule(t, &tmod);
   if (IsVarTerm(t)) {
-    Yap_Error(INSTANTIATION_ERROR, t, "call/1");
+    Yap_ThrowError(INSTANTIATION_ERROR, t, "call/1");
     LOCAL_PrologMode &= ~TopGoalMode;
     return (FALSE);
   }
@@ -1958,7 +1959,7 @@ Term Yap_RunTopGoal(Term t, bool handle_errors) {
     Functor f = FunctorOfTerm(t);
 
     if (IsBlobFunctor(f)) {
-      Yap_Error(TYPE_ERROR_CALLABLE, t, "call/1");
+      Yap_ThrowError(TYPE_ERROR_CALLABLE, t, "call/1");
       LOCAL_PrologMode &= ~TopGoalMode;
       return (FALSE);
     }
@@ -1969,7 +1970,7 @@ Term Yap_RunTopGoal(Term t, bool handle_errors) {
     pt = RepAppl(t) + 1;
     arity = ArityOfFunctor(f);
   } else {
-    Yap_Error(TYPE_ERROR_CALLABLE, Yap_TermToIndicator(t, tmod), "call/1");
+    Yap_ThrowError(TYPE_ERROR_CALLABLE, Yap_TermToIndicator(t, tmod), "call/1");
     LOCAL_PrologMode &= ~TopGoalMode;
     return (FALSE);
   }
@@ -2001,7 +2002,7 @@ Term Yap_RunTopGoal(Term t, bool handle_errors) {
 
 #if !USE_SYSTEM_MALLOC
   if (LOCAL_TrailTop - HeapTop < 2048) {
-    Yap_Error(RESOURCE_ERROR_TRAIL, TermNil,
+    Yap_ThrowError(RESOURCE_ERROR_TRAIL, TermNil,
               "unable to boot because of too little Trail space");
   }
 #endif
@@ -2031,7 +2032,7 @@ static void do_restore_regs(Term t, int restore_all USES_REGS) {
 static Int restore_regs(USES_REGS1) {
   Term t = Deref(ARG1);
   if (IsVarTerm(t)) {
-    Yap_Error(INSTANTIATION_ERROR, t, "support for coroutining");
+    Yap_ThrowError(INSTANTIATION_ERROR, t, "support for coroutining");
     return (FALSE);
   }
   if (IsAtomTerm(t))
@@ -2050,7 +2051,7 @@ static Int restore_regs2(USES_REGS1) {
   Int d;
 
   if (IsVarTerm(t)) {
-    Yap_Error(INSTANTIATION_ERROR, t, "support for coroutining");
+    Yap_ThrowError(INSTANTIATION_ERROR, t, "support for coroutining");
     return (FALSE);
   }
   d0 = Deref(ARG2);
@@ -2058,7 +2059,7 @@ static Int restore_regs2(USES_REGS1) {
     do_restore_regs(t, TRUE PASS_REGS);
   }
   if (IsVarTerm(d0)) {
-    Yap_Error(INSTANTIATION_ERROR, d0, "support for coroutining");
+    Yap_ThrowError(INSTANTIATION_ERROR, d0, "support for coroutining");
     return (FALSE);
   }
   if (!IsIntegerTerm(d0)) {
diff --git a/C/qlyr.c b/C/qlyr.c
index cd67ce30a..2a59eb349 100755
--- a/C/qlyr.c
+++ b/C/qlyr.c
@@ -1113,17 +1113,23 @@ static Int qload_program(USES_REGS1) {
 YAP_file_type_t Yap_Restore(const char *s) {
   CACHE_REGS
 
-  FILE *stream = Yap_OpenRestore(s);
+      int lvl = push_text_stack();
+  const char *tmp = Yap_AbsoluteFile(s, true);
+
+  FILE *stream = Yap_OpenRestore(tmp);
   if (!stream)
     return -1;
   GLOBAL_RestoreFile = s;
-  if (do_header(stream) == NIL)
+  if (do_header(stream) == NIL) {
+    pop_text_stack(lvl);
     return YAP_PL;
+  }
   read_module(stream);
   setBooleanGlobalPrologFlag(SAVED_PROGRAM_FLAG, true);
   fclose(stream);
   GLOBAL_RestoreFile = NULL;
   LOCAL_SourceModule = CurrentModule = USER_MODULE;
+  pop_text_stack(lvl);
   return YAP_QLY;
 }
 
diff --git a/C/yap-args.c b/C/yap-args.c
index dce1edeee..880d6da3c 100755
--- a/C/yap-args.c
+++ b/C/yap-args.c
@@ -142,7 +142,7 @@ static void init_globals(YAP_init_args *yap_init) {
   }
 
   if (yap_init->QuietMode) {
-    setVerbosity(TermSilent);
+    setBooleanLocalPrologFlag(VERBOSE_LOAD_FLAG, TermFalse);
   }
 }
 
diff --git a/H/YapLFlagInfo.h b/H/YapLFlagInfo.h
index 5949bc5c9..0269c16e2 100644
--- a/H/YapLFlagInfo.h
+++ b/H/YapLFlagInfo.h
@@ -52,6 +52,9 @@ YAP_FLAG(AUTOLOAD_FLAG, "autoload", true, booleanFlag, "false", NULL),
   YAP_FLAG(CALL_COUNTING_FLAG, "call_counting", true, booleanFlag, "true",
              NULL),
 
+/**< Indicates YAP is running within the compiler. */
+  YAP_FLAG(COMPILING_FLAG, "compiling", false, booleanFlag,
+             "true", NULL),
 /**< support for coding systens, YAP relies on UTF-8 internally.
  */
     YAP_FLAG(ENCODING_FLAG, "encoding", true, isatom, "utf-8", getenc),
@@ -69,9 +72,10 @@ YAP_FLAG(AUTOLOAD_FLAG, "autoload", true, booleanFlag, "false", NULL),
                  */
   YAP_FLAG(LANGUAGE_MODE_FLAG, "language_mode", true, isatom, "yap",
              NULL),
-    YAP_FLAG(STACK_DUMP_ON_ERROR_FLAG, "stack_dump_on_error", true, booleanFlag,
+/**< Show the execution stack in exceptions. */
+  YAP_FLAG(STACK_DUMP_ON_ERROR_FLAG, "stack_dump_on_error", false, booleanFlag,
              "true", NULL),
-             /**<`
+             /**<
 
         If `true` show a stack dump when YAP finds an error. The default is
         `off`.
@@ -91,19 +95,20 @@ Report the syntax error and generate an error (default).
 + `quiet`
 Just fail
 */
-    YAP_FLAG(SYNTAX_ERRORS_FLAG, "syntax_errors", true, synerr, "error",
-             NULL),
-             /**<
-           If bound, set the current working or type-in module to the argument,
-           which must be an atom. If unbound, unify the argument with the current
-           working module.
-
-           */
-             YAP_FLAG(TYPEIN_MODULE_FLAG, "typein_module", true, isatom, "user",
+  YAP_FLAG(SYNTAX_ERRORS_FLAG, "syntax_errors", true, synerr, "error",
+	   NULL),
+/**<
+   If bound, set the current working or type-in module to the argument,
+   which must be an atom. If unbound, unify the argument with the current
+   working module.
+   
+*/
+  YAP_FLAG(TYPEIN_MODULE_FLAG, "typein_module", true, isatom, "user",
              typein),
 
 
 
+
 /**<
 
     If `normal` allow printing of informational and banner messages,
@@ -131,8 +136,8 @@ Just fail
         is `true` by default except if YAP is booted with the `-L`
         flag.
      */
-	YAP_FLAG(VERBOSE_LOAD_FLAG, "verbose_load", true, booleanFlag, "true", NULL),
-	/**<
+  YAP_FLAG(VERBOSE_LOAD_FLAG, "verbose_load", true, booleanFlag, "true", NULL),
+/**<
 
   If the second argument is bound to a stream, set user_error to
   this stream. If the second argument is unbound, unify the argument with
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 219c2b7f0..dfceaa6ee 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -1,4 +1,5 @@
 set (LIBRARY_PL
+INDEX.yap
   apply.yap
   apply_macros.yap
   arg.yap
diff --git a/library/INDEX.yap b/library/INDEX.yap
new file mode 100644
index 000000000..b0881a922
--- /dev/null
+++ b/library/INDEX.yap
@@ -0,0 +1 @@
+%% auto-loading is not really supported in YAP.
diff --git a/library/autoloader.yap b/library/autoloader.yap
index 486a38656..7b0cebe9f 100644
--- a/library/autoloader.yap
+++ b/library/autoloader.yap
@@ -122,5 +122,6 @@ find_predicate(G,ExportingModI) :-
 	functor(G, Name, Arity),
 	ensure_loaded(File).
 
-:- ensure_loaded('INDEX').
+
+:-       ensure_loaded('INDEX').
 
diff --git a/library/lists.yap b/library/lists.yap
index e1c85f902..a9aa9061f 100644
--- a/library/lists.yap
+++ b/library/lists.yap
@@ -360,7 +360,7 @@ prefix([], _).
 prefix([Elem | Rest_of_part], [Elem | Rest_of_whole]) :-
   prefix(Rest_of_part, Rest_of_whole).
 
-%   remove_duplicates(List, Pruned)
+%%   remove_duplicates(+List, Pruned)
 %   removes duplicated elements from List.  Beware: if the List has
 %   non-ground elements, the result may surprise you.
 
@@ -369,6 +369,23 @@ remove_duplicates([Elem|L], [Elem|NL]) :-
 	delete(L, Elem, Temp),
 	remove_duplicates(Temp, NL).
 
+%%   remove_identical_duplicates(List, Pruned)
+%   removes duplicated elements from List.  
+remove_identical_duplicates([], []).
+remove_identical_duplicates([Elem|L], [Elem|NL]) :-
+	delete_identical(L, Elem, Temp),
+	remove_identical_duplicates(Temp, NL).
+
+
+delete_identical([],_, []).
+delete_identical([H|L],Elem,Temp)  :-
+    H == Elem,
+    !,
+	delete_identical(L, Elem, Temp).
+delete_identical([H|L], Elem, [H|Temp]) :-
+	delete_identical(L, Elem, Temp).
+
+
 
 %   same_length(?List1, ?List2)
 %   is true when List1 and List2 are both lists and have the same number
diff --git a/library/matrix.yap b/library/matrix.yap
index 806a9e5e5..4053121cc 100644
--- a/library/matrix.yap
+++ b/library/matrix.yap
@@ -667,6 +667,10 @@ Unify  _NElems_ with the type of the elements in  _Matrix_.
 	foldl( norm_dim, Dims0, Dims, Bases, 1, _Size ),
 	matrix_new( floats , Dims, X ),
 	matrix_base(X, Bases).
+( X <== '[]'(Dims0, static.array) of floats ) :-
+    atom(X), !,
+	foldl( norm_dim, Dims0, Dims, Bases, 1, _Size ),
+	static_array( Size, floats, X ).
 ( X <== '[]'(Dims0, array) of (I:J) ) :- !,
 	foldl( norm_dim, Dims0, Dims, Bases, 1, Size ),
 	matrix_seq(I, J, Dims, X),
@@ -762,6 +766,23 @@ rhs('[]'(Args, RHS), Val) :-
 	;
 	  matrix_get_range( X1, NArgs, Val )
 	).
+rhs('[]'([Args], floats(RHS)), Val) :-
+    atom(RHS),
+    integer(Args),
+    !,
+    array_element(RHS,Args,Val).
+rhs('[]'(Args, RHS), Val) :-
+	!,
+	rhs(RHS, X1),
+	matrix_dims( X1, Dims, Bases),
+	maplist( index(Range), Args, Dims, Bases, NArgs),
+	(
+	 var(Range)
+	->
+	  array_element( X1, NArgs, Val )
+	;
+	  matrix_get_range( X1, NArgs, Val )
+	).
 rhs('..'(I, J), [I1|Is]) :- !,
 	rhs(I, I1),
 	rhs(J, J1),
@@ -952,19 +973,25 @@ mtimes(I1, I2, V) :-
 % three types of matrix: integers, floats and general terms.
 %
 
-matrix_new(terms,Dims, '$matrix'(Dims, NDims, Size, Offsets, Matrix) ) :-
+matrix_new(terms.terms,Dims, '$matrix'(Dims, NDims, Size, Offsets, Matrix) ) :-
 	length(Dims,NDims),
 	foldl(size, Dims, 1, Size),
 	maplist(zero, Dims, Offsets),
 	functor( Matrix, c, Size).
-matrix_new(ints,Dims,Matrix) :-
+matrix_new(opaque.ints,Dims,Matrix) :-
 	length(Dims,NDims),
 	new_ints_matrix_set(NDims, Dims, 0, Matrix).
-matrix_new(floats,Dims,Matrix) :-
+matrix_new(opaque.floats,Dims,Matrix) :-
 	length(Dims,NDims),
 	new_floats_matrix_set(NDims, Dims, 0.0, Matrix).
 
 
+matrix_new(array.Type(Size), Dims, Data, '$array'(Id) ) :-
+	length(Dims,NDims),
+	foldl(size, Dims, 1, Size),
+	maplist(zero, Dims, Offsets),
+	functor( Matrix, c, Size),
+	new_array(Size,Type,Dims,Data),
 matrix_new(terms, Dims, Data, '$matrix'(Dims, NDims, Size, Offsets, Matrix) ) :-
 	length(Dims,NDims),
 	foldl(size, Dims, 1, Size),
diff --git a/packages/ProbLog/problog_examples/learn_graph.pl b/packages/ProbLog/problog_examples/learn_graph.pl
index 5f29b8062..35f439ed3 100644
--- a/packages/ProbLog/problog_examples/learn_graph.pl
+++ b/packages/ProbLog/problog_examples/learn_graph.pl
@@ -17,7 +17,7 @@
 :- use_module(library(matrix)).
 
 :- use_module(('../problog_learning')).
-:- stop_low_level_trace.
+
 %%%%
 % background knowledge
 %%%%
diff --git a/packages/ProbLog/problog_examples/learn_graph_lbdd.pl b/packages/ProbLog/problog_examples/learn_graph_lbdd.pl
index 19b9b5373..458a504ed 100644
--- a/packages/ProbLog/problog_examples/learn_graph_lbdd.pl
+++ b/packages/ProbLog/problog_examples/learn_graph_lbdd.pl
@@ -14,12 +14,21 @@
 % will run 20 iterations of learning with default settings
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-:- use_module(library(problog_learning)).
+:- use_module('../problog_lbfgs').
+
+
+%:- set_problog_flag(init_method,(Query,K,Bdd,problog:problog_exact_lbdd(Query,Bdd))).
+
+%:- if(true).
+:- use_module('kbgraph').
 
 %%%%
 % background knowledge
 %%%% 
 % definition of acyclic path using list of visited nodes
+
+/*:- else. 
+
 path(X,Y) :- path(X,Y,[X],_).
 
 path(X,X,A,A).
@@ -37,6 +46,8 @@ edge(X,Y) :- dir_edge(X,Y).
 absent(_,[]).
 absent(X,[Y|Z]):-X \= Y, absent(X,Z).
 
+:- endif.
+*/   
 %%%%
 % probabilistic facts 
 % - probability represented by t/1 term means learnable parameter
@@ -71,11 +82,11 @@ example(13,path(4,5),0.57).
 example(14,path(4,6),0.51).
 example(15,path(5,6),0.69).
 % some examples for learning from proofs:
-example(16,(dir_edge(2,3),dir_edge(2,6),dir_edge(6,5),dir_edge(5,4)),0.032).
-example(17,(dir_edge(1,6),dir_edge(2,6),dir_edge(2,3),dir_edge(3,4)),0.168).
-example(18,(dir_edge(5,3),dir_edge(5,4)),0.14).
-example(19,(dir_edge(2,6),dir_edge(6,5)),0.2).
-example(20,(dir_edge(1,2),dir_edge(2,3),dir_edge(3,4)),0.432).
+%example(16,(dir_edge(2,3),dir_edge(2,6),dir_edge(6,5),dir_edge(5,4)),0.032).
+%example(17,(dir_edge(1,6),dir_edge(2,6),dir_edge(2,3),dir_edge(3,4)),0.168).
+%example(18,(dir_edge(5,3),dir_edge(5,4)),0.14).
+%example(19,(dir_edge(2,6),dir_edge(6,5)),0.2).
+%example(20,(dir_edge(1,2),dir_edge(2,3),dir_edge(3,4)),0.432).
 
 %%%%%%%%%%%%%%
 % test examples of form test_example(ID,Query,DesiredProbability) 
@@ -98,3 +109,4 @@ test_example(33,path(5,4),0.57).
 test_example(34,path(6,4),0.51).
 test_example(35,path(6,5),0.69).
 
+
diff --git a/packages/ProbLog/problog_lbfgs.yap b/packages/ProbLog/problog_lbfgs.yap
index 3dc2f541a..79f0cac37 100644
--- a/packages/ProbLog/problog_lbfgs.yap
+++ b/packages/ProbLog/problog_lbfgs.yap
@@ -221,6 +221,7 @@
 :- use_module(library(system), [file_exists/1, shell/2]).
 :- use_module(library(rbtrees)).
 :- use_module(library(lbfgs)).
+:- reexport(library(matrix)).
 
 % load our own modules
 :- reexport(problog).
@@ -485,6 +486,8 @@ init_learning :-
 	succeeds_n_times(user:example(_,_,_,_),TrainingExampleCount),
 	assertz(example_count(TrainingExampleCount)),
 	format_learning(3,'~q training examples~n',[TrainingExampleCount]),
+	current_probs <== array[TrainingExampleCount ] of floats,
+	current_lls <== array[TrainingExampleCount ] of floats,
 	forall(tunable_fact(FactID,_GroundTruth),
 	       set_fact_probability(FactID,0.5)
 	      ),
@@ -514,9 +517,7 @@ update_values :-
 	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 	% delete old values
 	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-	retractall(query_probability_intern(_,_)),
-	retractall(query_gradient_intern(_,_,_,_)).
-
+    qp <== current_probs.
 
         %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 	% Check, if continuous facts are used.
@@ -579,71 +580,40 @@ bdd_input_file(Filename) :-
 	concat_path_with_filename(Dir,'input.txt',Filename).
 
 init_one_query(QueryID,Query,_Type) :-
-        %	format_learning(3,' ~q example ~q: ~q~n',[Type,QueryID,Query]),
-
-        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-	% if BDD file does not exist, call ProbLog
-	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-	 b_setval(problog_required_keep_ground_ids,false),
+    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+    % if BDD file does not exist, call ProbLog
+    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+    problog_flag(init_method,(Query,N,Bdd,user:graph2bdd(Query,N,Bdd))),
+    !,
+    b_setval(problog_required_keep_ground_ids,false),
 	 (QueryID mod 100 =:= 0 -> writeln(QueryID) ; true),
-	 Query =.. [_|Args],
-	 % problog_flag(init_method,(Query,N,Bdd,M:graph2bdd(Args,N,Bdd))),
-	 Bdd = bdd(Dir, Tree,
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-		   u3777777777/....777;;;;;;;;;;;;;;;;;;;666666666MapList),
-	  user:graph2bdd(Args,N,Bdd),
-	  rb_new(H0),
+	 Bdd = bdd(Dir, Tree,MapList),
+	  user:graph2bdd(Query,N,Bdd),
+ 	  rb_new(H0),
 	  maplist_to_hash(MapList, H0, Hash),
 	  tree_to_grad(Tree, Hash, [], Grad),
 	  % ;
 	  % Bdd = bdd(-1,[],[]),
 	  % Grad=[]
-		write('.'),
+	  write('.'),
 	  recordz(QueryID,bdd(Dir, Grad, MapList),_).
-
+init_one_query(QueryID,Query,_Type) :-
+    %	format_learning(3,' ~q example ~q: ~q~n',[Type,QueryID,Query]),
+        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+	% if BDD file does not exist, call ProbLog
+    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+	  b_setval(problog_required_keep_ground_ids,false),
+	  problog_flag(init_method,(Query,_K,Bdd,Call)),
+	  !,
+	  Bdd = bdd(Dir, Tree, MapList),
+	  %	  trace,
+ 	  once(Call),
+	  rb_new(H0),
+	  maplist_to_hash(MapList, H0, Hash),
+	  %Tree \= [],
+%	  writeln(Dir:Tree:MapList),
+	  tree_to_grad(Tree, Hash, [], Grads),
+	  recordz(QueryID,bdd(Dir, Grads, MapList),_).
 
 %========================================================================
 %=
@@ -738,6 +708,7 @@ mse_trainingset :-
 	logger_set_variable(mse_min_trainingset,MinError),
 	logger_set_variable(mse_max_trainingset,MaxError),
 	logger_set_variable(llh_training_queries,LLH_Training_Queries),
+%%%%%	format(' (~8f)~n',[MSE]).
 	format_learning(2,' (~8f)~n',[MSE]).
 
 tuple(t(X,Y),X,Y).
@@ -831,7 +802,6 @@ gradient_descent :-
 %	current_iteration(Iteration),
     findall(FactID,tunable_fact(FactID,_GroundTruth),L),
     length(L,N),
-%	leash(0),trace,
     lbfgs_initialize(N,X,0,Solver),
     forall(tunable_fact(FactID,_GroundTruth),
 	   set_fact( FactID, Slope, X)
@@ -861,59 +831,55 @@ set_tunable(I,Slope,P) :-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 % start calculate gradient
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-user:evaluate(LLH_Training_Queries, X,Grad,N,_,_) :-
-    %Handle = user_error,
-    example_count(TrainingExampleCount),
-    LLs <== array[TrainingExampleCount ] of floats,
-    Probs  <== array[N] of floats,
+user:evaluate(LLH_Training_Queries, X,Grad,N,_,_) :- 
+  %Handle = user_error,
+    LLs = current_lls,
+    Probs  = current_probs,
     problog_flag(sigmoid_slope,Slope),
     N1 is N-1,
     forall(between(0,N1,I),
 	   (Grad[I] <== 0.0, S <== X[I], sigmoid(S,Slope, P), Probs[I] <== P)
 	  ),
+    writeln(e0),
+        leash(0),trace,
     forall(
-	full_example(QueryID,QueryProb,BDD),
-	   compute_grad(QueryID, BDD, QueryProb,Grad, Probs, Slope,LLs)
+    user:example(QueryID,_Query,QueryProb),
+	compute_grad(QueryID, QueryProb,Grad, Probs, Slope,LLs)
     ),
+writeln(Grad),
     LLH_Training_Queries <== sum(LLs).
 
-full_example(QueryID,QueryProb,BDD) :-
-    user:example(QueryID,_Query,QueryProb,_),
-     recorded(QueryID,BDD,_),
-     BDD = bdd(_Dir, _GradTree, MapList),
-     MapList = [_|_].
 
-compute_grad(QueryID,BDD,QueryProb, Grad, Probs, Slope, LLs) :-
+
+compute_grad(QueryID,QueryProb, Grad, Probs, Slope, LLs) :-
+     recorded(QueryID,BDD,_),
     BDD = bdd(_Dir, _GradTree, MapList),
     bind_maplist(MapList, Slope, Probs),
-    recorded(QueryID,BDD,_),
     qprobability(BDD,Slope,BDDProb),
     LL is (BDDProb-QueryProb)*(BDDProb-QueryProb),
     LLs[QueryID] <== LL,
-%writeln( qprobability(BDD,Slope,BDDProb) ),
     forall(
-	member(I-_, MapList),
-	gradientpair(I, BDD,Slope,BDDProb, QueryProb, Grad, Probs)
-    ).
+	member(I-_,MapList),
+	gradientpair(Slope,BDDProb, QueryProb,Grad,Probs,BDD,I)
+	),
+writeln(LL).
 
-gradientpair(I, BDD,Slope,BDDProb, QueryProb, Grad, Probs) :-
-    qgradient(I, BDD, Slope, FactID, GradValue),
-    % writeln(FactID),
+
+gradientpair(Slope,BDDProb, QueryProb, Grad, Probs,BDD,I) :-
+   qgradient(I, BDD, Slope, FactID, GradValue),
     G0 <== Grad[FactID],
     Prob <== Probs[FactID],
-%writeln(    GN is G0-GradValue*(QueryProb-BDDProb)),
-   GN is G0-GradValue*2*Prob*(1-Prob)*(QueryProb-BDDProb),
-   %writeln(FactID:(G0->GN)),
-Grad[FactID] <== GN.
+    GN is G0-GradValue*2*Prob*(1-Prob)*(QueryProb-BDDProb),
+   Grad[FactID] <== GN.
 
 qprobability(bdd(Dir, Tree, _MapList), Slope, Prob) :-
 /*	query_probability(21,6.775948e-01). */
-	run_sp(Tree, Slope, 1.0, Prob0),
+	run_sp(Tree, Slope, 1, Prob0),
 	(Dir == 1 -> Prob0 = Prob ;  Prob is 1.0-Prob0).
 
 
-qgradient(I, bdd(Dir, Tree, _MapList), Slope, I, Grad) :-
-	run_grad(Tree, I, Slope, 0.0, Grad0),
+qgradient(I, bdd(Dir,Tree,_), Slope, I, Grad) :-
+	run_grad(Tree, I, Slope, 1.0, 0.0, Grad0),
 	( Dir = 1 -> Grad = Grad0 ; Grad is -Grad0).
 
 wrap( X, Grad, GradCount) :-
@@ -954,25 +920,25 @@ node_to_gradient_node(pn(P-G,X,L,R), H, gnoden(P,G,X,Id,PL,GL,PR,GR)) :-
 	(R == 1 -> GR=0, PR=1 ; R == 0 -> GR = 0, PR=0 ; R = PR-GR).
 
 run_sp([], _, P0, P0).
-run_sp(gnodep(P,_G, EP, _Id, PL, _GL, PR, _GR).Tree, Slope, _, PF) :-
+run_sp(gnodep(P,_G, EP, _Id, PL, _GL, PR, _GR).Tree, Slope, PL, PF) :-
 	P is EP*PL+ (1.0-EP)*PR,
 	run_sp(Tree, Slope, P, PF).
-run_sp(gnoden(P,_G, EP, _Id, PL, _GL, PR, _GR).Tree, Slope, _, PF) :-
-	P is EP*PL + (1.0-EP)*(1.0 - PR),
+run_sp(gnoden(P,_G, EP, _Id, PL, _GL, PR, _GR).Tree, Slope, PL, PF) :-
+    P is EP*PL + (1.0-EP)*(1.0 - PR),
 	run_sp(Tree, Slope, P, PF).
 
-run_grad([], _I, _, G0, G0).
-run_grad([gnodep(P,G, EP, Id, PL, GL, PR, GR)|Tree], I, Slope, _, GF) :-
+run_grad([], _I, _, _, G0, G0).
+run_grad([gnodep(P,G, EP, Id, PL, GL, PR, GR)|Tree], I, Slope, PL, GL, GF) :-
 	P is EP*PL+ (1.0-EP)*PR,
 	G0 is EP*GL + (1.0-EP)*GR,
 	% don' t forget the -X
 	( I == Id -> G is PL-PR ; G = G0 ),
-	run_grad(Tree, I, Slope, G, GF).
-run_grad([gnoden(P,G, EP, Id, PL, GL, PR, GR)|Tree], I, Slope, _, GF) :-
+	run_grad(Tree, I, Slope, P, G, GF).
+run_grad([gnoden(P,G, EP, Id, PL, GL, PR, GR)|Tree], I, Slope, PL, GL, GF) :-
 	P is EP*PL + (1.0-EP)*(1.0 - PR),
 	G0 is EP*GL  - (1.0 - EP) * GR,
 	( I == Id -> G is PL-(1.0-PR) ; G = G0 ),
-	run_grad(Tree, I, Slope, G, GF).
+	run_grad(Tree, I, Slope, P, G, GF).
 
 
 
@@ -986,7 +952,7 @@ log2prob(X,Slope,FactID,V) :-
 
 bind_maplist([], _Slope, _X).
 bind_maplist([Node-Pr|MapList], Slope, X) :-
-	Pr <== X[Node],
+    Pr <== X[Node],
 	bind_maplist(MapList, Slope, X).
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -996,7 +962,7 @@ user:progress(FX,_X,_G, _X_Norm,_G_Norm,_Step,_N,_Iteration,_Ls,-1) :-
     FX < 0, !,
     format('stopped on bad FX=~4f~n',[FX]).
 user:progress(FX,X,_G,X_Norm,G_Norm,Step,_N,_Iteration,Ls,0) :-
-    problog_flag(sigmoid_slope,Slope),
+    roblog_flag(sigmoid_slope,Slope),
     forall(tunable_fact(FactID,_GroundTruth), set_tunable(FactID,Slope,X)),
     current_iteration(CurrentIteration),
     retractall(current_iteration(_)),
@@ -1015,14 +981,14 @@ user:progress(FX,X,_G,X_Norm,G_Norm,Step,_N,_Iteration,Ls,0) :-
 %========================================================================
 
 init_flags :-
-%	prolog_file_name(queries,Queries_Folder), % get absolute file name for './queries'
-	prolog_file_name(output,Output_Folder), % get absolute file name for './output'
-	problog_define_flag(bdd_directory, problog_flag_validate_directory, 'directory for BDD scripts', Queries_Folder,learning_general),
-	problog_define_flag(output_directory, problog_flag_validate_directory, 'directory for logfiles etc', Output_Folder,learning_general,flags:learning_output_dir_handler),
-	problog_define_flag(log_frequency, problog_flag_validate_posint, 'log results every nth iteration', 1, learning_general),
-	problog_define_flag(rebuild_bdds, problog_flag_validate_nonegint, 'rebuild BDDs every nth iteration', 0, learning_general),
-	problog_define_flag(reuse_initialized_bdds,problog_flag_validate_boolean, 'Reuse BDDs from previous runs',false, learning_general),
-	problog_define_flag(check_duplicate_bdds,problog_flag_validate_boolean,'Store intermediate results in hash table',true,learning_general),
+    % prolog_file_name(queries,Queries_Folder), % get absolute file name for './queries'
+    prolog_file_name(output,Output_Folder), % get absolute file name for './output'
+    %	problog_define_flag(bdd_directory, problog_flag_validate_directory, 'directory for BDD scripts', Queries_Folder,learning_general),
+    problog_define_flag(output_directory, problog_flag_validate_directory, 'directory for logfiles etc', Output_Folder,learning_general,flags:learning_output_dir_handler),
+    problog_define_flag(log_frequency, problog_flag_validate_posint, 'log results every nth iteration', 1, learning_general),
+%	problog_define_flag(rebuild_bdds, problog_flag_validate_nonegint, 'rebuild BDDs every nth iteration', 0, learning_general),
+%	problog_define_flag(reuse_initialized_bdds,problog_flag_validate_boolean, 'Reuse BDDs from previous runs',false, learning_general),
+%	problog_define_flag(check_duplicate_bdds,problog_flag_validate_boolean,'Store intermediate results in hash table',true,learning_general),
 	problog_define_flag(init_method,problog_flag_validate_dummy,'ProbLog predicate to search proofs',(Query,Tree,problog:problog_kbest_as_bdd(Query,100,Tree)),learning_general,flags:learning_libdd_init_handler),
 	problog_define_flag(alpha,problog_flag_validate_number,'weight of negative examples (auto=n_p/n_n)',auto,learning_general,flags:auto_handler),
 	problog_define_flag(sigmoid_slope,problog_flag_validate_posnumber,'slope of sigmoid function',1.0,learning_general),
@@ -1057,3 +1023,4 @@ init_logger :-
 :- initialization(init_flags).
 
 :- initialization(init_logger).
+
diff --git a/packages/ProbLog/problog_learning_lbdd.yap b/packages/ProbLog/problog_learning_lbdd.yap
index cc11b6559..3a0f00aef 100644
--- a/packages/ProbLog/problog_learning_lbdd.yap
+++ b/packages/ProbLog/problog_learning_lbdd.yap
@@ -70,7 +70,7 @@
 % "Original License" means this Artistic License as Distributed with the
 % Standard Version of the Package, in its current version or as it may
 % be modified by The Perl Foundation in the future.
-% 
+ 
 % "Source" form means the source code, documentation source, and
 % configuration files for the Package.
 % 
@@ -587,7 +587,7 @@ empty_bdd_directory.
 set_default_gradient_method :-
     problog_flag(continuous_facts, true), 
     !,
-    problog_flag(init_method,OldMethod),
+    problog_flag(init_method,_OldMethod),
     format_learning(2,'Theory uses continuous facts.~nWill use problog_exact/3 as initalization method.~2n',[]),
     set_problog_flag(init_method,(Query,Probability,BDDFile,ProbFile,problog_exact_save(Query,Probability,_Status,BDDFile,ProbFile))).
 set_default_gradient_method :-
@@ -595,9 +595,10 @@ set_default_gradient_method :-
     !,
     format_learning(2,'Theory uses tabling.~nWill use problog_exact/3 as initalization method.~2n',[]),
     set_problog_flag(init_method,(Query,Probability,BDDFile,ProbFile,problog_exact_save(Query,Probability,_Status,BDDFile,ProbFile))).
-set_default_gradient_method :-
-    problog_flag(init_method,(gene(X,Y),N,Bdd,graph2bdd(X,Y,N,Bdd))),
+/*set_default_gradient_method :-
+    problog_flag(init_method,(Goal,N,Bdd,graph2bdd(X,Y,N,Bdd))),
     !.
+*/
 set_default_gradient_method :-
     set_problog_flag(init_method,(Query,1,BDD,
 	problog_kbest_as_bdd(user:Query,1,BDD))).
@@ -618,24 +619,36 @@ bdd_input_file(Filename) :-
 	problog_flag(output_directory,Dir),
 	concat_path_with_filename(Dir,'input.txt',Filename).
 
+init_one_query(QueryID,Query,_Type) :-
+    %	format_learning(3,' ~q example ~q: ~q~n',[Type,QueryID,Query]),
+
+        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+	% if BDD file does not exist, call ProbLog
+	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+	  b_setval(problog_required_keep_ground_ids,false),
+	  problog_flag(libbdd_init_method,(Query,Bdd,Call)),
+	  !,
+	  Bdd = bdd(Dir, Tree, MapList),
+%	  trace,
+	  once(Call),
+	  rb_new(H0),
+	  maplist_to_hash(MapList, H0, Hash),
+	  Tree \= [],
+%	  writeln(Dir:Tree:MapList),
+	  tree_to_grad(Tree, Hash, [], Grad).
+
 init_one_query(QueryID,Query,Type) :-
 %	format_learning(3,' ~q example ~q: ~q~n',[Type,QueryID,Query]),
 
         %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 	% if BDD file does not exist, call ProbLog
 	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-	(
-	 recorded(QueryID, _, _)
-	->
-	 format_learning(3,' Reuse existing BDD ~q~n~n',[QueryID])
-	 ;
 	  b_setval(problog_required_keep_ground_ids,false),
-	  problog_flag(init_method,(Query,N,Bdd,graph2bdd(X,Y,N,Bdd))),
-	  Query =.. [_,X,Y]
-	  ->
+	  problog_flag(init_method,(Query,N,Bdd,_)),
+	  !,
 	  Bdd = bdd(Dir, Tree, MapList),
 	  (
-	      graph2bdd(X,Y,N,Bdd)
+	      user:graph2bdd(Query,N,Bdd)
 	  ->
 	  rb_new(H0),
 	  maplist_to_hash(MapList, H0, Hash),
@@ -645,22 +658,7 @@ init_one_query(QueryID,Query,Type) :-
 	  Bdd = bdd(-1,[],[]),
 	  Grad=[]
 	  ),
-	  recordz(QueryID,bdd(Dir, Grad, MapList),_)
-	 ;
-	  b_setval(problog_required_keep_ground_ids,false),
-	  rb_new(H0),
-	  problog_flag(init_method,(Query,NOf,Bdd,problog_kbest_as_bdd(Call,1,Bdd))),
-	  strip_module(Call,_,gene(X,Y)),
-	  !,
-	  Bdd = bdd(Dir, Tree, MapList),
-%	  trace,
-	  problog:problog_kbest_as_bdd(user:gene(X,Y),1,Bdd),
-	  maplist_to_hash(MapList, H0, Hash),
-	  Tree \= [],
-	  %put_code(0'.),
-	  tree_to_grad(Tree, Hash, [], Grad),
-	 recordz(QueryID,bdd(Dir, Grad, MapList),_)
-	).
+	  recordz(QueryID,bdd(Dir, Grad, MapList),_).
 init_one_query(_QueryID,_Query,_Type) :-
     throw(unsupported_init_method).
 
@@ -1568,6 +1566,7 @@ init_flags :-
 	problog_define_flag(rebuild_bdds, problog_flag_validate_nonegint, 'rebuild BDDs every nth iteration', 0, learning_general),
 	problog_define_flag(reuse_initialized_bdds,problog_flag_validate_boolean, 'Reuse BDDs from previous runs',false, learning_general),	
 	problog_define_flag(check_duplicate_bdds,problog_flag_validate_boolean,'Store intermediate results in hash table',true,learning_general),
+	problog_define_flag(libbdd_init_method,problog_flag_validate_dummy,'ProbLog predicate to search proofs',(Query,Tree,problog:problog_kbest_as_bdd(Query,100,Tree)),learning_general,flags:learning_libdd_init_handler),
 	problog_define_flag(init_method,problog_flag_validate_dummy,'ProbLog predicate to search proofs',(Query,Tree,problog:problog_kbest_as_bdd(Query,100,Tree)),learning_general,flags:learning_libdd_init_handler),
 	problog_define_flag(alpha,problog_flag_validate_number,'weight of negative examples (auto=n_p/n_n)',auto,learning_general,flags:auto_handler),
 	problog_define_flag(sigmoid_slope,problog_flag_validate_posnumber,'slope of sigmoid function',1.0,learning_general),
diff --git a/pl/consult.yap b/pl/consult.yap
index b5c09eb82..c15b050dc 100644
--- a/pl/consult.yap
+++ b/pl/consult.yap
@@ -309,6 +309,7 @@ load_files(Files0,Opts) :-
     '$load_files__'(user_input, M, [consult(reconsult),stream(S)|Opts], Call).
 '$load_files'(Files, M, Opts, Call) :-
     '$load_files__'(Files, M, Opts, Call).
+
 '$load_files__'(Files, M, Opts, Call) :-
     '$lf_option'(last_opt, LastOpt),
     '$show_consult_level'(LC),
@@ -545,6 +546,7 @@ load_files(Files0,Opts) :-
        '$reexport'( TOpts, ParentF, Reexport, ImportList, File ),
        print_message(informational, loaded( loaded, F, M, T, H)),
        working_directory( _, OldD),
+       set_prolog_flag(compiling,false),
        '$exec_initialization_goals',
        '$current_module'(_M, Mod).
 '$start_lf'(_, Mod, Stream, TOpts, UserFile, File, _Reexport, _Imports) :-
diff --git a/pl/imports.yap b/pl/imports.yap
index 31856c77a..416799689 100644
--- a/pl/imports.yap
+++ b/pl/imports.yap
@@ -35,9 +35,11 @@ fail.
 % parent module mechanism
 %% system has priority
 '$get_predicate_definition'(_ImportingMod:G,prolog:G) :-
+    nonvar(G),
     '$pred_exists'(G,prolog).
 %% I am there, no need to import
 '$get_predicate_definition'(Mod:Pred,Mod:Pred) :-
+    nonvar(Pred),
     '$pred_exists'(Pred, Mod).
 %% export table
 '$get_predicate_definition'(ImportingMod:G,ExportingMod:G0) :-
@@ -45,13 +47,13 @@ fail.
 %% parent/user
 '$get_predicate_definition'(ImportingMod:G,ExportingMod:G0) :-
     ( '$parent_module'(ImportingMod, PMod) ), %; PMod = user),
-    ('$pred_exists'(PMod,G0), PMod:G0 = ExportingMod:G;
+    (nonvar(G0),'$pred_exists'(G0,PMod), PMod:G0 = ExportingMod:G;
      recorded('$import','$import'(ExportingMod,PMod,G0,G,_,_),_)
     ).
 %% autoload`
-'$get_predicate_definition'(ImportingMod:G,ExportingMod:G) :-
-    current_prolog_flag(autoload, true),
-    '$autoload'(G, ImportingMod, ExportingMod, swi).
+%'$get_predicate_definition'(ImportingMod:G,ExportingMod:G) :-
+%    current_prolog_flag(autoload, true),
+%    '$autoload'(G, ImportingMod, ExportingMod, swi).
 
 
 '$predicate_definition'(Imp:Pred,Exp:NPred) :-
diff --git a/pl/messages.yap b/pl/messages.yap
index 6d5418555..3cae1b7d9 100644
--- a/pl/messages.yap
+++ b/pl/messages.yap
@@ -1044,9 +1044,8 @@ prolog:print_message(Severity, Msg) :-
   ),
   !.
 prolog:print_message(Level, _Msg) :-
+    current_prolog_flag(compiling, true),
   current_prolog_flag(verbose_load, false),
-    '$show_consult_level'(LC),
-    LC > 0,
   Level \= error,
   Level \= warning,
   !.
diff --git a/pl/meta.yap b/pl/meta.yap
index fc6e91444..6168d5ffe 100644
--- a/pl/meta.yap
+++ b/pl/meta.yap
@@ -478,15 +478,14 @@ meta_predicate(P) :-
 expand_goal(Input, Output) :-
     '$expand_meta_call'(Input, none, Output ).
 
-'$expand_meta_call'(G, HVars, MF:GF ) :- 
-	source_module(SM),
-	'$yap_strip_module'(SM:G, M, IG),
-	'$is_metapredicate'(IG, M),
-	'$expand_goals'(IG, _, GF0, M, SM, M, HVars-G),
-	!,
-	'$yap_strip_module'(M:GF0, MF, GF).
+'$expand_meta_call'(G, HVars, MF:GF ) :-
+    source_module(SM),
+    '$yap_strip_module'(G, M, IG),
+    '$is_metapredicate'(IG, M),
+    '$expand_goals'(IG, _, GF0, M, SM, M, HVars-G),
+    !,
+    '$yap_strip_module'(M:GF0, MF, GF).
 '$expand_meta_call'(G, _HVars, M:IG ) :- 
-	source_module(SM),
-	'$yap_strip_module'(SM:G, M, IG).
+    '$yap_strip_module'(G, M, IG).
 
 %% @}
diff --git a/pl/preds.yap b/pl/preds.yap
index dae99f594..2e37b45dd 100644
--- a/pl/preds.yap
+++ b/pl/preds.yap
@@ -474,12 +474,11 @@ predicate_erased_statistics(P0,NCls,Sz,ISz) :-
 Defines the relation:  _P_ is a currently defined predicate whose name is the atom  _A_.
 */
 current_predicate(A0,T0) :-
-    
     ( nonvar(T0) -> '$yap_strip_module'(T0, M, T) ; T0 = T ),
-    ( nonvar(A0) -> '$yap_strip_module'(A0, MA0, A) ; A0 = A ),
+    ( nonvar(A0) -> '$yap_strip_module'(M:A0, MA0, A) ; A0 = A ),
     M = MA0,
     (
-	var(M)
+	nonvar(M)
     ->
     true
     ;
@@ -487,11 +486,13 @@ current_predicate(A0,T0) :-
     ),
     % M is bound
     (
-    '$current_predicate'(A,M,T,user)
+    '$current_predicate'(A,M,T,user),
+    functor(T, A, _)
     ;
-    '$imported_predicate'(M:T, M1T1), M1T1 \= M:T
-    ),
-    functor(T, A, _).
+    '$get_predicate_definition'(M:T,M1:_T1),
+    M\=M1,
+    functor(T, A, _)
+    ).
 
 
 /** @pred  system_predicate( ?_P_ )
diff --git a/pl/qly.yap b/pl/qly.yap
index 65018ec27..132d00e36 100755
--- a/pl/qly.yap
+++ b/pl/qly.yap
@@ -229,9 +229,9 @@ qend_program :-
 % there is some ordering between flags.
 'x_yap_flag'(language, V) :-
 	yap_flag(language, V).
-  %if silent keep silent, otherwise use the saved state.
-  'x_yap_flag'(verbose, _) :- !.
-  'x_yap_flag'(verbose_load, _) :- !.
+%if silent keep silent, otherwise use the saved state.
+'x_yap_flag'(verbose, _) :- !.
+'x_yap_flag'(verbose_load, _) :- !.
 'x_yap_flag'(M:P, V) :-
 	current_module(M),
 	yap_flag(M:P, V).
diff --git a/pl/top.yap b/pl/top.yap
index 157730be2..1f05b24d9 100644
--- a/pl/top.yap
+++ b/pl/top.yap
@@ -602,16 +602,18 @@ write_query_answer( Bindings ) :-
 '$enable_debugging':-
     current_prolog_flag(debug, false), !.
 '$enable_debugging' :-
-	'__NB_setval__'('$debug_status', state(creep, 0, stop)),
+	nb_setval('$debug_status', state(false,creep, 0, stop)),
     '$trace_on', !,
     '$creep'.
 '$enable_debugging'.
 
 '$trace_on' :-
-    '__NB_getval__'('$trace', on, fail).
+    '__NB_getval__'('$debug_status', state(_,Creep, GN, Spy), fail),
+    nb_setval('$debug_status', state(true,Creep, GN, Spy)).
 
 '$trace_off' :-
-    '__NB_getval__'('$trace', off, fail).
+    '__NB_getval__'('$debug_status', state(_,Creep, GN, Spy), fail),
+    nb_setval('$debug_status', state(false,Creep, GN, Spy)).
 
 '$cut_by'(CP) :- '$$cut_by'(CP).
 
diff --git a/pl/undefined.yap b/pl/undefined.yap
index b93b9dd77..ff751dc69 100644
--- a/pl/undefined.yap
+++ b/pl/undefined.yap
@@ -93,16 +93,13 @@ undefined_query(G0, M0, Cut) :-
 '$undefp_search'(M0:G0, MG) :-
     '$predicate_definition'(M0:G0, MG), !.
 
-% undef handler
-'$undefp'([M0|G0],true) :-
-	% make sure we do not loop on undefined predicates
-	setup_call_cleanup(
-			   '$undef_setup'(Action,Debug,Current),
-			   '$get_undefined_predicate'( M0:G0, MG ),
-			   '$undef_cleanup'(Action,Debug,Current)
-	),
-	'$undef_error'(Action, M0:G0,  MG).
-
+'$undef_error'(error,  Mod:Goal) :-
+    '$do_error'(existence_error(procedure,Mod:Goal), Mod:Goal).
+'$undef_error'(warning,Mod:Goal) :-
+    '$program_continuation'(PMod,PName,PAr),
+    print_message(warning,error(existence_error(procedure,Mod:Goal), context(Mod:Goal,PMod:PName/PAr))).
+'$undef_error'(fail,_).
+ 
 '$undef_setup'(Action,Debug,Current) :-
     yap_flag( unknown, Action, fail),
     yap_flag( debug, Debug, false),
@@ -112,6 +109,34 @@ undefined_query(G0, M0, Cut) :-
     yap_flag( unknown, _, Action),
     yap_flag( debug, _, Debug).
 
+'$found_undefined_predicate'( M0:G0, M:G ) :-
+    '$pred_exists'(unknown_predicate_handler(_,_,_), user),
+    '$yap_strip_module'(M0:G0,  EM0, GM0),
+    user:unknown_predicate_handler(GM0,EM0,M:G),
+    !.
+'$found_undefined_predicate'( M0:G0, _ ) :-
+    yap_flag( unknown, _, Action),
+    '$undef_error'(Action,  M0:G0 ).
+
+'$search_undef'(M0:G0, M:G) :-
+% make sure we do not loop on undefined predicates
+	setup_call_cleanup(
+			   '$undef_setup'(Action,Debug,Current),
+			   '$get_undefined_predicate'( M0:G0, M:G ),
+			   '$undef_cleanup'(Action,Debug,Current)
+	),
+	!.
+'$search_undef'(M0:G0, M:G) :-
+    '$found_undefined_predicate'( M0:G0, M:G ).
+
+%%  undef handler:
+%  we found an import, and call again
+%  we have user code in the unknown_predicate
+%  we fail, output a message, and just generate an exception.
+'$undefp'([M0|G0],ok) :-
+    '$search_undef'(M0:G0, M:G),
+	'$trace'(M:G).
+
 :- abolish(prolog:'$undefp0'/2).
 :- '$undefp_handler'('$undefp'(_,_), prolog).
 
@@ -126,28 +151,6 @@ The unknown predicate, informs about what the user wants to be done
 
 */
 
-'$undef_error'(_, _,  M:G) :-
-	nonvar(M),
-	nonvar(G),
-	!,
-	'$start_creep'([M|G], creep).
-'$undef_error'(_, M0:G0, M:G) :-
-    '$pred_exists'(unknown_predicate_handler(_,_,_,_), user),
-    '$yap_strip_module'(M0:G0,  EM0, GM0),
-    user:unknown_predicate_handler(GM0,EM0,M:G),
-    !,
-    '$start_creep'([M|G], creep).
-'$undef_error'(error,  Mod:Goal,_) :-
-    '$do_error'(existence_error(procedure,Mod:Goal), Mod:Goal).
-'$undef_error'(warning,Mod:Goal,_) :-
-    '$program_continuation'(PMod,PName,PAr),
-    print_message(warning,error(existence_error(procedure,Mod:Goal), context(Mod:Goal,PMod:PName/PAr))),
-    %'$start_creep'([prolog|fail], creep),
-    fail.
-'$undef_error'(fail,_Goal,_,_Mod) :-
-   % '$start_creep'([prolog|fail], creep),
-    fail.
-
 unknown(P, NP) :-
     yap_flag( unknown, P, NP ).