The Head-Driven Phrase Structure Grammar (HPSG) is a grammar theory developed by Pollard and Sag (1985). It uses a uniform formalism and is organized in a modular way which makes it attractive for Natural language processing.
... is 2.41 and the average family size is 2.88.
In the town the population is spread out with 20.6% under the age of 18, 5.0% from 18 to 24, 26.8% from 25 to 44, 27.7% ...