Introduction

We use language to express concepts and ideas. The richness of languages means that there are many different ways to express the same concept. We can use different words in different grammatical constructions, all to express the same concept. Here lies the problem with search; we might express a concept one way. The entry in the index for an occurrence of that concept will not be an exact match. The designers of the index and search applications attempt to solve this difficult problem.

One of the many advantages claimed for digital asset management is the ability to quickly search the content repository to find relevant information. Whether the application lives up to that claim depends very much on the precision and recall abilities of the search engine. Although cataloguing and search are different operations, and undertaken by different users, the two are usually components of the same application. Consequently, the catalogue index is prepared for a specific search engine.

There are two ways to find content. If you are familiar with the taxonomy, you can search through a directory tree until you locate the wanted file. The other way is to use some form of search engine. The first route assumes that you are familiar with the contents of the file. As a repository grows in size this rapidly becomes untenable. Most people can even lose track of files on the local drive on their desktop computer.

Databases have long had the facility to query the data to retrieve...