We notice that the concatenation consistently outperforms the gated-attention mechanism for both training and testing instructions. We suspect that the gated-attention is useful in the scenarios where objects are described in terms of multiple attributes, but it has no to harming effect when it comes to the order connectors. 
 Question: Why they conclude that the usage of Gated-Attention provides no competitive advantage against concatenation in this setting?
concatenation consistently outperforms the gated-attention mechanism for both training and testing instructions