Published online by Cambridge University Press: 25 October 2011
Motivated by the violations of the context-free grammar G0, discussed in the previous chapter, we now extend the CFG formalism with additional mechanisms that will facilitate the expression of information that is missing in G0 in a uniform and compact way. The core idea is to incorporate into the grammar the properties of symbols in terms of which violations of G0 were stated. Properties are represented by means of feature structures. As we show in this chapter, feature structures provide a natural representation for the kind of linguistic information that grammars specify, a natural (partial) order on the amount of information stored in these representations and an efficient operation for combining the information stored in two representations.
We begin this chapter with an overview of feature structures, motivating their use as a representation of linguistic information (Section 2.1). We then present four different views of these entities. We begin with feature graphs (Section 2.2), which are just a special case of ordinary (labeled, directed) graphs. The well-studied mathematical and computational properties of graphs make this view easy to understand and very suitable for computational implementation. This view, however, introduces a level of arbitrariness, which is expressed in the identities of the nodes. We therefore introduce two additional views. One, simply called feature structures (Section 2.3), is defined as equivalence classes of isomorphic feature graphs, abstracting over node identities. The other, called abstract feature structures (Section 2.4), uses sets rather than graphs and is easy to work with mathematically.
To save this book to your Kindle, first ensure email@example.com is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.