We adapt techniques from sapertagging — a relatively recent technique that performs complex lexical tagging before full parsing (Bangalore and Joshi, 1999; Clark, 2002) — for chart realization in OpenCCG, an open-source NLP toolkit for CCG .

The OpenCCG surface realizer is based on Steed-man’s (2000) version of CCG elaborated with Baldridge and Kruijff’s multi-modal extensions for lexically specified derivation control (Baldridge, 2002; Baldridge and Kruijff, 2003) and hybrid logic dependency semantics (Baldridge and Kruijff, 2002).

(2007) describe an ongoing effort to engineer a grammar from the CCGbank (Hockenmaier and Steedman, 2007) — a corpus of CCG derivations derived from the Penn Treebank — suitable for realization with OpenCCG.

Changes to the derivations are necessary to reflect the lexicalized treatment of coordination and punctuation assumed by the multi-modal version of CCG that is implemented in OpenCCG.

We have introduced a novel type of supertagger, which we have dubbed a hypertagger, that assigns CCG category labels to elementary predications in a structured semantic representation with high accuracy at several levels of tagging ambiguity in a fashion reminiscent of (Bangalore and Rambow, 2000).

We have also shown that, by integrating this hypertagger with a broad-coverage CCG chart realizer, considerably faster realization times are possible (approximately twice as fast as compared with a realizer that performs simple lexical lookups) with higher BLEU, METEOR and exact string match scores.

In lexicalized grammatical formalisms such as Lexicalized Tree Adjoining Grammar (Schabes et al., 1988, LTAG), Combinatory Categorial Grammar (Steedman, 2000, CCG ) and Head-Driven Phrase-Structure Grammar (Pollard and Sag, 1994, HPSG), it is possible to separate lexical category assignment — the assignment of informative syntactic categories to linguistic objects such as words or lexical predicates — from the combinatory processes that make use of such categories — such as parsing and surface realization.

combination thereof, as in the CCG parser in (Hockenmaier, 2003) or the chart realizer in (Carroll and Oepen, 2005).

Supertagging has been more recently extended to a multitagging paradigm in CCG (Clark, 2002; Curran et al., 2006), leading to extremely efficient parsing with state-of-the-art dependency recovery (Clark and Curran, 2007).

In the next section, we show that a supertagger for CCG realization, or hypertagger, can reduce the problem of search errors by focusing the search space on the most likely lexical categories.

The standard set of rules defined in Combinatory Categorial Grammar ( CCG ) fails to provide satisfactory analyses for a number of syntactic structures found in natural languages.

These structures can be analyzed elegantly by augmenting CCG with a class of rules based on the combinator D (Curry and Feys, 1958).

CCG uses a universal set of syntactic rules based on the B, T, and S combinators of combinatory logic (Curry and Feys, 1958): (2) Br ((Bf)g)w = f(gw) T: T51: f = fa: SI ((Sf)g)w = fw(gw) CCG functors are functions over strings of symbols,

The rules of this multimodal version of CCG (Baldridge, 2002; Baldridge and Kruijff, 2003) are derived as theorems of a Categorial Type Logic (CTL, Moortgat (1997)).

This treats CCG as a compilation of CTL proofs, providing a principled, grammar-internal basis for restrictions on the CCG rules, transferring language-particular restrictions on rule application to the lexicon, and allowing the CCG rules to be viewed as grammatical universals (Baldridge and Kruijff, 2003; Steedman and Baldridge, To Appear).

Combinatory Categorial Grammar ( CCG , Steedman (2000)) is a compositional, semantically transparent formalism that is both linguistically expressive and computationally tractable.

A distinctive aspect of CCG is that it provides a very flexible notion of constituency.

that even with its flexibility, CCG as standardly defined is not permissive enough for certain linguistic constructions and greater incrementality.

We use these brackets to determine new gold-standard CCG derivations in Section 3.

Combinatory Categorial Grammar ( CCG ) (Steedman, 2000) is a type-driven, lexicalised theory of

This is an advantage of CCG , allowing it to recover long-range dependencies without the need for postprocessing, as is the case for many other parsers.

This section describes the process of converting the Vadas and Curran (2007a) data to CCG derivations.

CCGbank (Hockenmaier and Steedman, 2007) is the primary English corpus for Combinatory Categorial Grammar ( CCG ) (Steedman, 2000) and was created by a semiautomatic conversion from the Penn Treebank.

However, CCG is a binary branching grammar, and as such, cannot leave NP structure underspecified.

:e Structure with CCG

In all heavily lexicalised formalisms, such as LTAG, CCG , LPG and HPSG, the lexicon plays a key role in parsing.

Originally described by Bangalore and J oshi (1994) for use in LTAG parsing, it has also been used very successfully for CCG (Clark, 2002).

The supertags used in each formalism differ, being elementary trees in LTAG and CCG categories for CCG .

This would be similar to the CCG supertagging mechanism and is likely to give generous speedups at the possible expense of precision, but it would be illuminating to discover how this tradeoff plays out in our setup.

This could be considered a form of supertagging as used in LTAG and CCG .

While POS taggers such as TreeTagger are common, and there some supertaggers are available, notably that of Clark and Curran (2007) for CCG , no standard supertagger exists for HPSG.

SCF and DR: These more linguistically informed features are constructed based on the grammatical relations generated by the C&C CCG parser (Clark and Curran, 2007).

We extract features on the basis of the output generated by the C&C CCG parser.

One explanation for the poor performance could be that we use all the frames generated by the CCG parser in our experiment.

To see if Levin-selected SCFs are more effective for AVC, we match each SCF generated by the C&C CCG parser (CCG-SCF) to one of 78 Levin-defined SCFs, and refer to the resulting SCF set as unfiltered-Levin-SCF.