Syntactic and semantic disambiguation of numeral strings using an n-gram method

This paper describes the interpretation of numerals, and strings including numerals, composed of a number and words or symbols that indicate whether the string is a SPEED, LENGTH, or whatever. The interpretation is done at three levels: lexical, syntactic, and semantic. The system employs three interpretation processes: a word trigram constructor with tokeniser, a rule-based processor of number strings, and n-gram based disambiguation of meanings. We extracted numeral strings from 378 online newspaper articles, finding that, on average, they comprised about 2.2% of the words in the articles. We chose 287 of these articles to provide unseen test data (3251 numeral strings), and used the remaining 91 articles to provide 886 numeral strings for use in manually extracting n-gram constraints to disambiguate the meanings of the numeral strings. We implemented six different disambiguation methods based on category frequency statistics collected from the sample data and on the number of word trigram constraints of each category. Precision ratios for the six methods when applied to the test data ranged from 85.6% to 87.9%.