diff --git a/src/persian/CatPes.gf b/src/persian/CatPes.gf
index af48895ab..e79528dfd 100644
--- a/src/persian/CatPes.gf
+++ b/src/persian/CatPes.gf
@@ -15,13 +15,13 @@ concrete CatPes of Cat = CommonX - [Adv] ** open ResPes, Prelude in {
     Cl = ResPes.Clause ;
     ClSlash = {
       subj : Str ;
-      vp : ResPes.VPHTense => Polarity => Order => Str ;
+      vp : ResPes.TAnt => Polarity => Order => Str ;
       c2 : ResPes.Compl
       } ;
     Imp = {s : Polarity => ImpForm => Str} ;
 
 ---- Question
-    QCl = {s : ResPes.VPHTense => Polarity => QForm => Str} ;
+    QCl = {s : ResPes.TAnt => Polarity => QForm => Str} ;
 
     IP = {s: Str ; n : Number};
 
@@ -32,7 +32,7 @@ concrete CatPes of Cat = CommonX - [Adv] ** open ResPes, Prelude in {
 ---- Relative
 
     RCl = {
-      s : ResPes.VPHTense => Polarity => Order => Agr => Str ;
+      s : ResPes.TAnt => Polarity => Order => Agr => Str ;
     --  c : Case
       } ;
     RP = {s: Str ; a:RAgr};
diff --git a/src/persian/ResPes.gf b/src/persian/ResPes.gf
index d67e2ea74..199092cf7 100644
--- a/src/persian/ResPes.gf
+++ b/src/persian/ResPes.gf
@@ -57,9 +57,16 @@ resource ResPes = MorphoPes ** open Prelude,Predef in {
  -----------------------
 param
   VVForm = Indic | Subj ;
+  VVTense = VVPres | VVPerf | VVPast ; -- VVPast Anteriority ???
 
 oper
 
+  -- TODO: all forms
+  ta2vvt : TAnt -> VVTense = \ta -> case ta of {
+    TA Pres Anter => VVPerf ;
+    TA Past _     => VVPast ;
+    _ => VVPres } ;
+
   VV : Type = Verb ** {
       isAux : Bool ;
       compl : VVForm ; -- indicative or subjunctive
@@ -67,21 +74,22 @@ oper
       } ;
 
   VPH : Type = Verb ** {
-      comp  : Agr => Str; -- complements of a verb, agr for e.g. CompCN "I am human/we are humans"
-      vComp : Agr => Anteriority => Str; -- when a verb is used as a complement of an auxiliary verb. Unlike ‘comp’ or ‘obj’, this type of complement follows the auxiliary verb.
+      comp  : Agr => Str; -- complements of a verb, agr for ReflVP "I/you see myself/yourself" and CompCN "I am human/we are humans"
+      vComp : Agr => VVTense => Str; -- when a verb is used as a complement of an auxiliary verb. Unlike ‘comp’ or ‘obj’, this type of complement follows the auxiliary verb.
       obj   : Str ; -- object of a verb; so far only used for A ("paint it black")
       subj  : VType ;
       ad    : Str ;
       embComp : Str ; -- when a declarative or interrogative sentence is used as a complement of a verb.
-      defVV : Bool ; -- whether a defective VV has been added
+      isVV  : Bool ; -- whether a VV has been added
+      isDef : Bool ; -- whether a the VV is defective
       } ;
 
   showVPH = overload {
-    showVPH : VerbForm -> Agr -> VPH -> Str = showVPH' Simul ;
-    showVPH : Anteriority -> VerbForm -> Agr -> VPH -> Str = showVPH'
+    showVPH : VerbForm -> Agr -> VPH -> Str = showVPH' VVPres ;
+    showVPH : VVTense -> VerbForm -> Agr -> VPH -> Str = showVPH'
   } ;
 
-  showVPH' : Anteriority -> VerbForm -> Agr -> VPH -> Str =
+  showVPH' : VVTense -> VerbForm -> Agr -> VPH -> Str =
     \ant,vf,agr,vp -> vp.ad ++ vp.comp ! agr ++ vp.obj
                    ++ vp.prefix ++ vp.s ! vf
                    ++ vp.vComp ! agr ! ant ++ vp.embComp ;
@@ -91,14 +99,9 @@ oper
   VPHSlash : Type = VPH ** {c2 : Compl} ;
 
  param
+    TAnt = TA Tense Anteriority ;
 
-    VPHTense =
-     TA Tense Anteriority
-     | VVVForm -- AR 21/3/2018 for mustCl after Nasrin
-     | VRoot1  -- AR 22/3/2018 for mustCl past after Nasrin
-    ;
-
-    VType = VIntrans | VTrans | VTransPost ;
+    VType = VIntrans | VTrans | VTransPost ; -- TODO: find out if needed
 
 oper
 
@@ -107,15 +110,13 @@ oper
     ad,
     obj,
     embComp = [];
-    defVV = False ;
+    isDef,isVV = False ;
     comp = \\_ => [] ;
     vComp = \\_,_ => [] } ;
 
    predVc : (Verb ** {c2,c1 : Str}) -> VPHSlash = \verb ->
     predV verb ** {c2 = {s = verb.c1 ; ra = []} } ;
 
-
-
 ---------------------
 -- VP complementation
 ---------------------
@@ -130,11 +131,11 @@ oper
     comp = \\a => appComp vp.c2 (obj ! a) ++ vp.comp ! a
     } ;
 
-  insertVV : Bool -> (Agr => Anteriority => Str) -> VPH -> VPH =
-    \isDef,infcl,vp -> vp ** {
-      defVV = True; --isDef ;
-      vComp = \\agr,ant => vp.vComp ! agr ! ant ++ infcl ! agr ! ant ;
-    } ;
+  insertVV : VV -> VPH -> VPH = \vv,vp -> predV vv ** {
+    vComp = \\a,t => vp.vComp ! a ! t ++ complVV vv vp ! a ! t ;
+    isVV = True ;
+    isDef = vv.isDef ;
+  } ;
 
   embComp : Str -> VPH -> VPH = \str,vp -> vp ** {
     embComp = vp.embComp ++ str ;
@@ -150,14 +151,20 @@ oper
 
 ---- AR 14/9/2017 trying to fix isAux = True case by inserting conjThat
 ---- but don't know yet how False should be affect
-  infVV : VV -> VPH -> (Agr => Anteriority => Str) = \vv,vp ->
+  complVV : VV -> VPH -> (Agr => VVTense => Str) = \vv,vp ->
     \\agr,ant => if_then_Str vv.isAux conjThat [] ++
-      case <ant,vv.compl> of {
-        <_Simul,Subj> => showVPH (VSubj Pos agr) agr vp ;
-        <_Simul,Indic> => showVPH (VAor Pos agr) agr vp
-        -- TODO: confirm <Anter,_> => showVPH PerfStem agr vp ++ subjAux Pos agr
-    } ;
+      case <ant,vv.compl,vv.isDef> of {
+        -- Auxiliaries with full inflection: complement in subjunctive
+        <_,_,False>    => showVPH (VSubj Pos agr) agr vp ; --
 
+       -- Auxiliaries with defective inflection: complement inflects in tense
+        <VVPres,Subj,True>  => showVPH (VSubj Pos agr) agr vp ;
+        <VVPres,Indic,True> => showVPH (VAor Pos agr) agr vp ;
+        <VVPast,_,True>       => showVPH (VPast Pos agr) agr vp ;
+--        <VVPast Anter> => showVPH PerfStem agr vp ++ pluperfAux Pos agr ; -- TODO do we need this?
+        <VVPerf,_,True>       => showVPH PerfStem agr vp ++ subjAux Pos agr ;
+        _ => showVPH (VSubj Pos agr) agr vp ---- TODO more forms ?
+    } ;
 
   insertAdV : Str -> VPH -> VPH = \ad,vp -> vp ** {
     ad = vp.ad ++ ad ;
@@ -168,37 +175,35 @@ oper
 ---------------------------
 --- Clauses
 ---------------------------
-  Clause : Type = {s : VPHTense => Polarity => Order => Str} ;
-  SlClause : Type = {quest : Order => Str ; subj : Str ; vp : VPHTense => Polarity => Order => Str} ;
-
+  Clause : Type = {s : TAnt => Polarity => Order => Str} ;
+  SlClause : Type = {quest : Order => Str ; subj : Str ; vp : TAnt => Polarity => Order => Str} ;
 ---- AR 18/9/2017 intermediate SClause to preserve SOV in e.g. QuestionPes.QuestSlash
 
-  clTable : VPH -> (Agr => VPHTense => Polarity => Str) = \vp ->
+ -- TODO: check the VV forms with defective verbs
+  clTable : VPH -> (Agr => TAnt => Polarity => Str) = \vp ->
     \\agr,vt,pol => vp.prefix ++ case vt of {
       TA Pres Simul => vp.s ! ImpPrefix pol ++ vp.s ! VAor pol agr ; -- for reg. verbs, VAor pol is invariant and negation comes in ImpPrefix.
       TA Pres Anter => vp.s ! VPerf pol agr ;
       TA Past Simul => vp.s ! VPast pol agr ;
       TA Past Anter =>
-         case vp.defVV of {
+         case vp.isDef of {
            True  => vp.s ! ImpPrefix pol ++ vp.s ! VAor pol agr ;
            False => vp.s ! PerfStem ++ pluperfAux pol agr } ;
       TA Fut  Simul =>
-         case vp.defVV of {
+         case vp.isDef of {
            True  => vp.s ! ImpPrefix pol ++ vp.s ! VAor pol agr ;
            False => futAux pol agr ++ vp.s ! PastStem
          } ; -- PastStem is, despite the name, used for future too. /IL
       TA Fut  Anter =>
-         case vp.defVV of {
+         case vp.isDef of {
            True  => vp.s ! VPerf pol agr ;
            False => "خواسته" ++ pluperfAux pol agr ++ vp.s ! PastStem
          } ; -- verb form need to be confirmed
       TA Cond Simul => vp.s ! VSubj pol agr ;
       TA Cond Anter =>
-         case vp.defVV of {
+         case vp.isDef of {
            True  => vp.s ! VSubj pol agr ;
-           False => vp.s ! PerfStem ++ subjAux pol agr } ; -- verb form to be confirmed
-      VVVForm    => vp.s ! VSubj Pos agr ; -- AR 21/3/2018
-      VRoot1     => vp.s ! PastStem        -- AR 22/3/2018
+           False => vp.s ! PerfStem ++ subjAux pol agr } -- verb form to be confirmed
   } ;
 
   mkClause : NP -> VPH -> Clause = \np,vp ->
@@ -210,25 +215,21 @@ oper
               { ODir => [];
                 OQuest => "آیا" } ;
     subj = np.s !  Bare ;
-    vp = \\vt,b,ord =>
-      let vps = clTable vp ! np.a ! vt ! b ;
-          ant = case vp.defVV of {
-                  True  => case vt of {TA Pres _ => Simul ; TA _ a => Anter ; _ => Simul}  ;
-                  False => Simul }
+    vp = \\ta,p,ord =>
+      let vps = clTable vp ! np.a ! ta ! p ;
+          vvt = ta2vvt ta ;
        in vp.ad ++ vp.comp ! np.a ++ vp.obj ++ vps
-       ++ vp.vComp ! np.a ! ant ++ vp.embComp
+       ++ vp.vComp ! np.a ! vvt ++ vp.embComp
   };
 
---Clause : Type = {s : VPHTense => Polarity => Order => Str} ;
+--Clause : Type = {s : TAnt => Polarity => Order => Str} ;
   mkSClause : Str -> Agr -> VPH -> Clause = \subj,agr,vp -> {
-    s = \\vt,b,ord =>
-      let vps = clTable vp ! agr ! vt ! b ;
+    s = \\ta,p,ord =>
+      let vps = clTable vp ! agr ! ta ! p ;
           quest = case ord of { ODir => [] ; OQuest => "آیا" } ;
-          ant = case vp.defVV of {
-                  True  => case vt of {TA Pres _ => Simul ; TA _ a => Anter ; _ => Simul}  ;
-                  False => Simul }
+          vvt = ta2vvt ta ;
        in quest ++ subj ++ vp.ad ++ vp.comp ! agr ++ vp.obj
-       ++ vps ++ vp.vComp ! agr ! ant ++ vp.embComp
+       ++ vps ++ vp.vComp ! agr ! vvt ++ vp.embComp
   };
 
   predProg : VPH -> VPH = \verb -> verb ** {
@@ -236,10 +237,7 @@ oper
       ImpPrefix _ => [] ;
       VAor  p a => haveVerb.s ! VAor  Pos a ++ verb.s ! ImpPrefix p ++ verb.s ! VAor Pos a ;
       VPast p a => haveVerb.s ! VPast Pos a ++ verb.s ! ImpPrefix p ++ verb.s ! VPast Pos a ; -- negation in ImpPrefix
-	    -- VF pol (VFPres PrImperf) agr => haveVerb.s ! VF Pos (VFPres PrImperf) agr ++ verb.s ! VF pol (VFPres PrImperf) agr ;
-      -- VF pol (VFPast PstAorist) agr => haveVerb.s ! VF Pos (VFPast PstAorist) agr ++ verb.s ! VF pol (VFPast PstAorist) agr ;
-      -- VF pol (VFPast PstImperf) agr => haveVerb.s ! VF Pos (VFPast PstAorist) agr ++ verb.s ! VF pol (VFPast PstImperf) agr ;
-	    _ => verb.s ! vh } ;
+	    _ => verb.s ! vh } ; -- TODO more forms
     subj = VIntrans
     } ;
 
diff --git a/src/persian/SentencePes.gf b/src/persian/SentencePes.gf
index a82ace94f..c0f91eeac 100644
--- a/src/persian/SentencePes.gf
+++ b/src/persian/SentencePes.gf
@@ -12,9 +12,10 @@ concrete SentencePes of Sentence = CatPes ** open Prelude, ResPes,Predef in {
     ImpVP vp = {
       s = \\pol,n =>
         let agr = Ag (numImp n) P2 ;
-         in case vp.defVV of {
-              True  => vp.s ! VImp pol (numImp n) ++ vp.ad ++ vp.comp ! agr ++ vp.obj ++ vp.vComp ! agr ! Simul ++ vp.embComp;
-              False => vp.ad ++ vp.comp ! agr ++ vp.obj ++ vp.vComp ! agr ! Simul ++ vp.s ! VImp pol (numImp n) ++ vp.embComp }
+            vps = vp.prefix ++ vp.s ! VImp pol (numImp n)
+         in case vp.isVV of {
+              True  => vps ++ vp.ad ++ vp.comp ! agr ++ vp.obj ++ vp.vComp ! agr ! VVPres ++ vp.embComp ;
+              False => vp.ad ++ vp.comp ! agr ++ vp.obj ++ vp.vComp ! agr ! VVPres ++ vps ++ vp.embComp }
     } ;
 
     SlashVP np vp =
diff --git a/src/persian/StructuralPes.gf b/src/persian/StructuralPes.gf
index e3f880fb9..67d0afe03 100644
--- a/src/persian/StructuralPes.gf
+++ b/src/persian/StructuralPes.gf
@@ -20,7 +20,7 @@ concrete StructuralPes of Structural = CatPes **
   but_PConj = ss "اما" ;
   by8agent_Prep = ss "توسط" ;
   by8means_Prep = ss "با" ;
---  can8know_VV,can_VV = mkV "سکن" ** { isAux = True} ;
+--  can8know_VV,can_VV = mkVV (mkV "سکن") ;
   can_VV = mkVV (mkV_1 "توانستن") ; ---- AR
   during_Prep = ss ["در طول"] ;
   either7or_DConj = sd2 "یا" "یا" ** {n = Sg} ;
@@ -50,9 +50,9 @@ concrete StructuralPes of Structural = CatPes **
   most_Predet = ss "اکثر";
   much_Det = mkDet ["مقدار زیادی"]  Pl ;
   must_VV =
-    let must_V : V = defV "بایستن" "باید" "بایست" ;
-     in mkVV must_V ;
-   -- TODO:  ** {isDef=True} ; past tense forms with مجبور+beVerb
+    let must : VV = mkVV False subjunctive (defV "بایستن" "باید" "باید") ; -- "بایست" is different meaning?
+     in must ** {isDef=True} ;
+   -- TODO: past tense forms with مجبور+beVerb
   no_Utt = ss "نه" ;
   on_Prep = ss "روی" ;
   only_Predet = ss "فقط" ;
diff --git a/src/persian/VerbPes.gf b/src/persian/VerbPes.gf
index beb5d55e6..799da98d7 100644
--- a/src/persian/VerbPes.gf
+++ b/src/persian/VerbPes.gf
@@ -4,41 +4,35 @@ concrete VerbPes of Verb = CatPes ** open ResPes,Prelude in {
   flags optimize=all_subs ;
 
   lin
-    UseV  v = predV v ;
+    UseV = predV ;
     SlashV2a v = v ** predV v;
     Slash2V3 v np = {c2 = v.c3} **
       complSlash (predV v ** {c2 = v.c2}) np ;
-
     Slash3V3 v np = {c2 = v.c2} **
       complSlash (predV v ** {c2 = v.c3}) np ;
-
     ComplSlash = complSlash ;
 
-    ComplVV v vp = insertVV v.isDef (infVV v vp) (predV v) ;
+    ComplVV = insertVV ;
     ComplVS v s  = embComp (conjThat ++ s.s) (predV v) ;
     ComplVQ v q  = embComp (conjThat ++ q.s ! QIndir) (predV v) ;
     ComplVA v ap = insertObj (ap.s ! Bare) (predV v) ; -- check form of adjective
-    SlashV2V v vp = insertVV v.isDef (infVV v vp) (predV v) **{c2 = {s = v.c1 ; ra = []}} ;
 
+    SlashVV vv vps = vps ** insertVV vv vps ;
     SlashV2S v s  = v ** embComp (conjThat ++ s.s) (predV v) ;
     SlashV2Q v q  = v ** embComp (q.s ! QIndir) (predV v) ;
     SlashV2A v ap = v ** insertObj (ap.s ! Bare) (predV v) ; ---- paint it red , check form of adjective
-
-    SlashVV vv vps = vps ** insertVV vv.isDef (infVV vv vps) (predV vv) ;
-
+    SlashV2V v vp = insertVV v vp ** {c2 = {s = v.c1 ; ra = []}} ;
     SlashV2VNP v2v np vps =
-      let vvVP : VPH = insertVV v2v.isDef (infVV v2v vps) (predV v2v) ;
+      let vvVP : VPH = insertVV v2v vps ;
           vvVPS = vvVP ** {c2={s=v2v.c1 ; ra=v2v.c2}} ; -- TODO find out if it's a general rule; only one V2V in the lexicon /IL
        in complSlash vvVPS np ** {c2 = vps.c2} ;
 
-
-    UseComp comp = insertComp comp.s (predV beVerb) ;
-
     AdvVP vp adv = insertAdV adv.s vp ;
-
     AdVVP adv vp = insertAdV adv.s vp ;
     ReflVP v = insertCompPre reflPron v ;
     PassV2 v = predV v ; -- need to be fixed
+
+    UseComp comp = insertComp comp.s (predV beVerb) ;
     CompAP ap = {s = \\_ => ap.s ! Bare} ; -- check form of adjective
     CompAdv adv = {s = \\_ => adv.s } ;