English Disambiguation Grammar

The English disambiguation grammars, or English d-grammars, are a part of the English grammar and are used to improve the results of the tokenization and to control the application of t-rules. They follow the formalism described at UNL Grammar Specs and are used both in natural language analysis (UNLization) and in natural language generation (NLization).

UNLization

In natural language analysis, the d-grammar is used to control the tokenization of the English sentences, i.e., to prevent wrong lexical choices and to induce the best matches. The d-grammar comprises two different types of disambiguation rules, or d-rules:

• Negative (blocking) rules, where the probability is equal to 0, prevent lexical choices

  For instance, the rule (D)(BLK)(V)=0; informs that the sequence determiner+blank space+verb is not allowed, i.e., there cannot be a determiner before a verb.

• Positive rules, where the probability is more than 0, force lexical choices

  For instance, the rule (['s],V)(BLK)(GER)=1; informs that the entry ['s] as a verb is to be preferred before a gerund (there are three entries ['s] in the dictionary: the contracted form of "is", the particle used to form the genitive and a plural suffix; if this rule is not stated, the system would simply select the first one appearing in the dictionary with the highest frequency)

How to use d-grammars

D-grammars must be uploaded to or provided directly at the tab d-rules in IAN.

Examples of disambiguation rules

TOKENIZATION OF TEMPORARY WORDS (used to control hyper-segmentation)

(TEMP,^DIGIT,^W)(^BLK,^PUT,^STAIL)=0;

there must be a blank, a punctuation sign or the end of the sentence after a temporary word, i.e., a temporary word cannot be followed by other word, except for digits, as in "1st"

(^BLK,^PUT,^SHEAD)(TEMP,^W)=0;

there must be a blank, a punctuation sign or the beginning of the sentence before a temporary word, i.e., a temporary word cannot be preceded by other word

(TEMP)(PUT)(TEMP)=0; there cannot be two temporary words separated by punctuation mark

DETERMINERS X PRONOUNS (used to disambiguate pronouns from determiners, which come first in the dictionary)

(D,^AFT)({PUT,^BLK|STAIL})=0; 

determiners may not come at the end of the sentence or before a punctuation mark, except if their distribution is AFT, like "enough"

(D,^AFT)(BLK)({V|P|AAV})=0; 

determiners may not be precede verbs, prepositions or adjunct adverbs, except if their distribution is AFT

AUXILIARY VERBS X MAIN VERBS (have, be)

(AUX)(BLK)(^V,^[not])=0; 

an auxiliary verb must be followed by a verb or the words "not" or "to"

(AUX)(BLK)([not])(BLK)(^V)=0; 

if followed by "not", the auxiliary must be followed by a verb