Feature Instability as a Criterion for Selecting Potential Style Markers

We introduce a new measure on linguistic features, called stability, which captures the extent to which a language element such as a word or a syntactic construct is replaceable by semantically equivalent elements. This measure may be perceived as quantifying the degree of available “synonymy” for a language item. We show that frequent, but unstable, features are especially useful as discriminators of an author’s writing style.