Feature functions

This page is a description of all currently-implemented features in thrax. For instructions on implementing your own, see feature function implementation. Entries on this page should be added in this form:

feature name

Label: feature name as shown in output "name=value"

Included in: which value to add to features key in thrax.conf to include this feature

Mathematical description.

Probability of source phrase given target phrase

Label: SourcePhraseGivenTarget

Included in: phrase

For a rule like ( X \to \langle \alpha ;, \beta \rangle ), let ( c(\cdot) ) be the number of times a particular phrase has been seen among all the extracted rules. Then we calculate ( p(\alpha | \beta) = \frac{c(\alpha,\beta)}{c(\beta)} ) and the value of this feature is ( - \log{ p(\alpha|\beta)} ).