In the <cite>relaxed hybrid tree</cite>, however, each word is not only directly associated with exactly one semantic unit m, but also indirectly associated with all other semantic units that are predecessors of m. For example, the word w 3 now is directly associated with m b , but is also indirectly associated with m a . Both the hybrid tree and <cite>relaxed hybrid tree</cite> models define patterns at each level of their latent structure which specify how the words and child semantic units are organized at each level.