One key difference is that we disallow the unary pat-   The features are defined over the (n, m, h) tuples.
in practice, we define features at each level of the relaxed hybrid tree structure h. features are defined over (n, m) tuples where n is a contiguous sequence of natural language words (immediately or remotely) associated with the semantic unit m (recall that h contains both n and m, and each level of h simply consists of a semantic unit and a contiguous sequence of words).