Automatic Extraction of Fixed Multiword Expressions

Fixed multiword expressions are strings of words which together behave like a single word. This research establishes a method for the automatic extraction of such expressions. Our method involves three stages. In the first, a statistical measure is used to extract candidate bigrams. In the second, we use this list to select occurrences of candidate expressions in a corpus, together with their surrounding contexts. These examples are used as training data for supervised machine learning, resulting in a classifier which can identify target multiword expressions. The final stage is the estimation of the part of speech of each extracted expression based on its context of occurence. Evaluation demonstrated that collocation measures alone are not effective in identifying target expressions. However, when trained on one million examples, the classifier identified target multiword expressions with precision greater than 90%. Part of speech estimation had precision and recall of over 95%.