// f) | ((b & c) & e) | ((b & c) & f) | ((b & d) & e) | ((b & d) & f))
NonLeafExpressionNode exp15 = new NonLeafExpressionNode(Operator.AND);
NonLeafExpressionNode temp1 = new NonLeafExpressionNode(Operator.AND);
temp1.addChildExp(new NonLeafExpressionNode(Operator.OR, new LeafExpressionNode("a"),
new LeafExpressionNode("b")));
temp1.addChildExp(new NonLeafExpressionNode(Operator.OR, new LeafExpressionNode("c"),
new LeafExpressionNode("d")));
exp15.addChildExp(temp1);
exp15.addChildExp(new NonLeafExpressionNode(Operator.OR, new LeafExpressionNode("e"),
new LeafExpressionNode("f")));
result = expander.expand(exp15);