Surprisingly Efficient Parsing for a Wide-Coverage Lexicalised-Grammar Parser

Add to your list(s) Download to your calendar using vCal

• Stephen Clark and Yue Zhang - University of Cambridge
• Friday 04 March 2011, 12:00-13:00
• FW26, Computer Laboratory.

If you have a question about this talk, please contact Thomas Lippincott.

In this talk we will describe two approaches to improving the efficiency of a wide-coverage CCG parser. The C&C parser (Clark and Curran, 2007) is already surprisingly efficient, parsing at around 30 sentences per second on standard hardware. This is surprising because the parser does not do any pruning at the parsing stage, but builds a complete packed chart. The efficiency comes from the use of a linear-time supertagger, which greatly reduces the search space, and highly optimised C++.

Despite the use of the supertagger, there is still a huge amount of ambiguity left in the chart. The first approach to improving speed will be to perform some pruning on the chart. We investigate standard beam search for chart-parsing—removing low-scoring items—as well as a novel, more aggressive technique which removes complete cells from the chart. Both techniques result in significant speed-ups.

The second approach is a novel technique which involves self-training the supertagger on large amounts of parser output. The speed of the parser is directly related to the number of supertags (CCG lexical categories) supplied by the supertagger for each word on average. The insight behind this approach is to recognise that the supertagger can easily be trained to predict which supertags the parsing model will eventually choose, resulting in a supertagger model which is much more tightly integrated with the parser.

This talk is part of the NLIP Seminar Series series.

This talk is included in these lists:

• All Talks (aka the CURE list)
• Cambridge Centre for Data-Driven Discovery (C2D3)
• Cambridge Forum of Science and Humanities
• Cambridge Language Sciences
• Cambridge talks
• Chris Davis' list
• Department of Computer Science and Technology talks and seminars
• FW26, Computer Laboratory
• Graduate-Seminars
• Guy Emerson's list
• Interested Talks
• Language Sciences for Graduate Students
• NLIP Seminar Series
• PMRFPS's
• Simon Baker's List
• Trust & Technology Initiative - interesting events
• bld31
• ndk22's list
• ob366-ai4er
• rp587

Note that ex-directory lists are not shown.