(2001), Schwartz and Hearst (2003) and Nadeau and Turney (2005), disambiguate the acronym by comparing its letters di-rectly to the initial letters in the possible long-forms and, therefore, would have difficulties in distinguishing between acronyms with similar long-forms (e.g., RA referring to Refractory anemia or Rheumatoid arthritis).
the first-order features in the instance vector contain the words from the entire abstract.