N-rule

Normalization rules are used to prepare the natural language input for automatic processing. They constitute the preprocessing module that applies over the input as a string and runs prior to the tokenization. The set of n-rules forms the Normalization Grammar, or N-Grammar.

Syntax

Normalization Rules follow the very general formalism

α:=β;

where the left side α is a condition statement, and the right side β is an action to be performed over α.

Roles of Normalization Rules

Normalization roles They have two roles:

• to normalize the input text (to replace abbreviations by their extend forms, to extend contractions, etc.)
• to segment the natural language text into sentences (i.e., to create the tags <SHEAD> (beginning of a sentence), <STAIL> (end of a sentence), <CHEAD> (beginning of a scope) and <CTAIL> (end of a scope) inside the input text). These sentences are used as sentence and clause boundaries, and define the units of processing of the Transformation and Disambiguation grammars.

Examples of Normalization rules

• Segmentation
  • ("/.*\./",%x):=(%x)(+STAIL,%y); (creates an STAIL node after any sequence of characters followed by "." (/.*\./);
  • ("/\(/",%x):=(+CHEAD,%y)(%x); (creates an CHEAD node before the opening of a parentheses (/\(/);
• Normalization
  • ("an "):=("a "); ("an apple" > "a apple")
  • ("don't"):=("do not"); ("I don't see" > "I do not see")