As shown in Table 1, there are five main categories of morphological processes, each of which has several subcategories, as detailed in Figure 2 (see Wu [2003] for a detailed description): r Affixation (MP and MS): r Splitting (MS) (i.e., a set of expressions that are separate words at the syntactic level but single words at the semantic level): £ Ñ 'already ate', where the bi-character word £Ñ 'eat' is split by the particle 'already'; r Merging (MM): ª 'on duty' + « 'off duty' → ª« 'on-off duty'; and r Head Particle (MHP) (i.e., expressions that are verb + comp): The second characteristic of MDWs is that they form stable Chinese character sequences in the corpus.
the components within the MDWs are strongly correlated (of high co-occurrence frequency), while the components at both ends have low correlations with words outside the sequence.