}
// if the item is a variable which is already bound
// and the value differs from the value of the triple
// which would be used as binding, a conflict is
// detected
else if (!literal.valueEquals(substitutionsLiteralRight.get(i))) {
System.out.println("Error " + this.toString() + ": "
+ itemName + ":" + substitutionsLiteralRight.get(i)
+ "<->" + literal);
System.out.println(oldBinding);
return null; // join within triple pattern!