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diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/RecursiveCommunicationGroup.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/RecursiveCommunicationGroup.java
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+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/RecursiveCommunicationGroup.java
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+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timeless;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.EnumMap;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.Set;
+
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.RederivableNode;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.PhasedSelector;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * A communication group representing either a single node where the
+ * node is a monotonicity aware one or a set of nodes that form an SCC. 
+ * 
+ * @author Tamas Szabo
+ * @since 2.4
+ */
+public class RecursiveCommunicationGroup extends CommunicationGroup {
+
+    private final Set<Mailbox> antiMonotoneMailboxes;
+    private final Set<Mailbox> monotoneMailboxes;
+    private final Set<Mailbox> defaultMailboxes;
+    private final Set<RederivableNode> rederivables;
+    private boolean currentlyDelivering;
+
+    /**
+     * @since 1.7
+     */
+    public RecursiveCommunicationGroup(final CommunicationTracker tracker, final Node representative, final int identifier) {
+        super(tracker, representative, identifier);
+        this.antiMonotoneMailboxes = CollectionsFactory.createSet();
+        this.monotoneMailboxes = CollectionsFactory.createSet();
+        this.defaultMailboxes = CollectionsFactory.createSet();
+        this.rederivables = new LinkedHashSet<RederivableNode>();
+        this.currentlyDelivering = false;
+    }
+
+    @Override
+    public void deliverMessages() {
+        this.currentlyDelivering = true;
+        
+        // ANTI-MONOTONE PHASE
+        while (!this.antiMonotoneMailboxes.isEmpty() || !this.defaultMailboxes.isEmpty()) {
+            while (!this.antiMonotoneMailboxes.isEmpty()) {
+                final Mailbox mailbox = this.antiMonotoneMailboxes.iterator().next();
+                this.antiMonotoneMailboxes.remove(mailbox);
+                mailbox.deliverAll(PhasedSelector.ANTI_MONOTONE);
+            }
+            while (!this.defaultMailboxes.isEmpty()) {
+                final Mailbox mailbox = this.defaultMailboxes.iterator().next();
+                this.defaultMailboxes.remove(mailbox);
+                mailbox.deliverAll(PhasedSelector.DEFAULT);
+            }
+        }
+
+        // REDERIVE PHASE
+        while (!this.rederivables.isEmpty()) {
+            // re-derivable nodes take care of their unregistration!!
+            final RederivableNode node = this.rederivables.iterator().next();
+            node.rederiveOne();
+        }
+
+        // MONOTONE PHASE
+        while (!this.monotoneMailboxes.isEmpty() || !this.defaultMailboxes.isEmpty()) {
+            while (!this.monotoneMailboxes.isEmpty()) {
+                final Mailbox mailbox = this.monotoneMailboxes.iterator().next();
+                this.monotoneMailboxes.remove(mailbox);
+                mailbox.deliverAll(PhasedSelector.MONOTONE);
+            }
+            while (!this.defaultMailboxes.isEmpty()) {
+                final Mailbox mailbox = this.defaultMailboxes.iterator().next();
+                this.defaultMailboxes.remove(mailbox);
+                mailbox.deliverAll(PhasedSelector.DEFAULT);
+            }
+        }
+        
+        this.currentlyDelivering = false;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return this.rederivables.isEmpty() && this.antiMonotoneMailboxes.isEmpty()
+                && this.monotoneMailboxes.isEmpty() && this.defaultMailboxes.isEmpty();
+    }
+
+    @Override
+    public void notifyHasMessage(final Mailbox mailbox, final MessageSelector kind) {
+        final Collection<Mailbox> mailboxes = getMailboxContainer(kind);
+        mailboxes.add(mailbox);
+        if (!this.isEnqueued && !this.currentlyDelivering) {
+            this.tracker.activateUnenqueued(this);
+        }
+    }
+
+    @Override
+    public void notifyLostAllMessages(final Mailbox mailbox, final MessageSelector kind) {
+        final Collection<Mailbox> mailboxes = getMailboxContainer(kind);
+        mailboxes.remove(mailbox);
+        if (isEmpty()) {
+            this.tracker.deactivate(this);
+        }
+    }
+
+    private Collection<Mailbox> getMailboxContainer(final MessageSelector kind) {
+        if (kind == PhasedSelector.ANTI_MONOTONE) {
+            return this.antiMonotoneMailboxes;
+        } else if (kind == PhasedSelector.MONOTONE) {
+            return this.monotoneMailboxes;
+        } else if (kind == PhasedSelector.DEFAULT) {
+            return this.defaultMailboxes;
+        } else {
+            throw new IllegalArgumentException(UNSUPPORTED_MESSAGE_KIND + kind);
+        }
+    }
+
+    public void addRederivable(final RederivableNode node) {
+        this.rederivables.add(node);
+        if (!this.isEnqueued) {
+            this.tracker.activateUnenqueued(this);
+        }
+    }
+
+    public void removeRederivable(final RederivableNode node) {
+        this.rederivables.remove(node);
+        if (isEmpty()) {
+            this.tracker.deactivate(this);
+        }
+    }
+
+    public Collection<RederivableNode> getRederivables() {
+        return this.rederivables;
+    }
+
+    @Override
+    public Map<MessageSelector, Collection<Mailbox>> getMailboxes() {
+        Map<PhasedSelector, Collection<Mailbox>> map = new EnumMap<>(PhasedSelector.class);
+        map.put(PhasedSelector.ANTI_MONOTONE, antiMonotoneMailboxes);
+        map.put(PhasedSelector.MONOTONE, monotoneMailboxes);
+        map.put(PhasedSelector.DEFAULT, defaultMailboxes);
+        return Collections.unmodifiableMap(map);
+    }
+    
+    @Override
+    public boolean isRecursive() {
+        return true;
+    }
+    
+}