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diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/tuple/BaseLeftInheritanceTuple.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/tuple/BaseLeftInheritanceTuple.java
new file mode 100644
index 00000000..03f9ea89
--- /dev/null
+++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/tuple/BaseLeftInheritanceTuple.java
@@ -0,0 +1,65 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2017, Gabor Bergmann, IncQueryLabs Ltd.
+ * 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.matchers.tuple;
+
+/**
+ * Common functionality of left inheritance tuple implementations.
+ * 
+ * <p>Left inheritance tuples inherit their first few elements from another tuple, 
+ * and extend it with additional "local" elements.
+ * 
+ * @author Gabor Bergmann
+ * @since 1.7
+ */
+public abstract class BaseLeftInheritanceTuple extends Tuple {
+
+    /**
+     * The number of elements that aren't stored locally, but inherited from an ancestor Tuple instead.
+     */
+    protected final int inheritedIndex;
+    /**
+     * This object contains the same elements as the ancestor on the first inheritedIndex positions
+     */
+    protected final Tuple ancestor;
+    
+    /**
+     * @param ancestor
+     */
+    public BaseLeftInheritanceTuple(Tuple ancestor) {
+        super();
+        this.ancestor = ancestor;
+        this.inheritedIndex = ancestor.getSize();
+    }
+
+    /**
+     * @return the number of local (non-inherited) elements
+     */
+    public abstract int getLocalSize();
+    
+    /**
+     * Optimized equals calculation (prediction: true, since hash values match)
+     */    
+    @Override
+    protected boolean internalEquals(ITuple other) {
+        if (other instanceof BaseLeftInheritanceTuple) {
+            BaseLeftInheritanceTuple blit = (BaseLeftInheritanceTuple) other;
+            if (blit.inheritedIndex == this.inheritedIndex) {
+                if (this.ancestor.equals(blit.ancestor)) {
+                    return localEquals(blit);
+                } else return false;
+            }
+        }
+        return super.internalEquals(other);
+    }
+
+    /**
+     * Checks the equivalence of local elements only, after ancestor tuple has been determined to be equal.
+     */
+    protected abstract boolean localEquals(BaseLeftInheritanceTuple other);
+}