diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/core/Occurrence.kt b/reactor/Core/src/jetbrains/mps/logic/reactor/core/Occurrence.kt
index 5a1b8940..976816c1 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/core/Occurrence.kt
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/core/Occurrence.kt
@@ -39,14 +39,14 @@ class Occurrence (observable: LogicalStateObservable,
     ConstraintOccurrence, ForwardingLogicalObserver, Justified
 {
 
-    var alive = true
+    var alive = false
 
     var stored = false
 
     val identity = System.identityHashCode(this)
 
     init {
-        revive(observable)
+//        revive(observable)
     }
 
     override fun constraint(): Constraint = constraint
@@ -64,18 +64,22 @@ class Occurrence (observable: LogicalStateObservable,
     override fun parentUpdated(logical: Logical<*>, controller: Controller) = doReactivate(controller)
 
     fun terminate(observable: LogicalStateObservable) {
-        for (a in arguments) {
-            if (a is Logical<*>) {
-                observable.removeForwardingObserver(a, this)
+        if (alive) {
+            for (a in arguments) {
+                if (a is Logical<*>) {
+                    observable.removeForwardingObserver(a, this)
+                }
             }
         }
         alive = false
     }
 
     fun revive(observable: LogicalStateObservable) {
-        for (a in arguments) {
-            if (a is Logical<*>) {
-                observable.addForwardingObserver(a, this)
+        if (!alive) {
+            for (a in HashSet(arguments)) { // avoid duplicate subscriptions
+                if (a is Logical<*>) {
+                    observable.addForwardingObserver(a, this)
+                }
             }
         }
         alive = true
diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/ConstraintsProcessing.kt b/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/ConstraintsProcessing.kt
index 25ebba97..e2b32b5f 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/ConstraintsProcessing.kt
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/ConstraintsProcessing.kt
@@ -212,7 +212,6 @@ internal class ConstraintsProcessing(private var dispatchingFront: Dispatcher.Di
      */
     fun processActivated(controller: Controller, active: Occurrence, parent: MatchJournal.MatchChunk, inStatus: FeedbackStatus) : FeedbackStatus {
         push()
-        assert(active.alive)
 
         val activationChunk: MatchJournal.OccChunk?
         if (!active.stored) {
@@ -223,6 +222,7 @@ internal class ConstraintsProcessing(private var dispatchingFront: Dispatcher.Di
             // defined (not null) & needed only for incremental execution
             activationChunk = journalIndex.activatingChunkOf(active)
         }
+        assert(active.alive)
 
         profiler.profile("dispatch_${active.constraint().symbol()}") {