Parsing Chinese with Combinatory Categorial Grammar: A Linguistic and Computational Study

Table 3

NCR subtypes in Chinese CCGbank (CASS).

	Argument-drop	POS-absorption^6	Topicalization	POS-shift
Frequency	16,680	2761	2675	2658
% of total	67.33%	11.14%	10.80%	10.73%
Unary	Yes	No	Yes	Yes

⁶ A pos-absorption rule allows one of the two categories participating in the derivation to absorb the other and result in itself. For example, S\NP NP ⟶ NP, in which the right NP absorbs the left S\NP. This pos-absorption rule violates CCG’s projection principle because S\NP finds its argument NP to its right (instead of left), disregarding the functionality stipulated in the structure head. However, as we have argued in Sections 3.1 and 3.2, this rule S\NP NP ⟶ NP indeed incorporates two subprocesses: S\NP ⟶ NP/NP and NP/NP NP ⟶ NP, in which the first step realizes an intransitive verb phrase of S\NP category as an attributive (Zhu’s realization), and then the second step combines the resulted attributive NP/NP with its noun head. Thus, the pos-absorption rules actually add more proof to our refined model for Chinese compositionality.