Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Definitions of special expressions used in this paper. An inner is a string inside a pair of parentheses, a left-chunk is a string before the left parenthesis, and an outer is a string extracted from the left-chunk and is the correspondent of the inner as a pair of an abbreviation and its expansion.
