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Smith 18 SYSTEM REVIEW Apple’s <strong>Spotlight</strong> application is tightly integrated with the Mac operating system. As such, its indexing and retrieval operations are closely guarded proprietary processes, discussed only in the broadest terms in corporate literature. Despite these restrictions, the above performance evaluation provides a good understanding of <strong>Spotlight</strong>’s underlying information retrieval model. What follows is a broad review of <strong>Spotlight</strong>’s information retrieval features, as deduced from the evaluation process. Search and retrieval issues that became apparent during the course of the evaluation are also noted. IR Model <strong>Spotlight</strong>’s underlying information retrieval model appears to be a classic Boolean model with binary weighting; that is, a document is either relevant (included in results set) or nonrelevant (excluded from results set). This is evidenced by the fact that results are presented in lexicographic order by file name, with no ranking algorithm used. Text operations <strong>Spotlight</strong>’s logical view of documents is full-text, and includes information relating to syntactic structure. Experimentation does not suggest the existence of any text normalization procedures. Specifically, there appears to be: No lexical analysis. For example, a <strong>Spotlight</strong> search on “full-text” will locate this paper; but it is excluded from the results list if the hyphen is excluded in the search query. No stopword removal. A search of the word ‘the’, for example yields 12,040 matches on the tested hard drive. This figure includes 1,1155 rich and plain text documents, and 443 PDF documents. No stemming. A search on the word ‘enter’ will return this paper in the results set, but fails to do so if the same word is searched with an added suffix of ‘-s’ or ‘-ing’. Text languages <strong>Spotlight</strong> indexes a broad range of text languages, including both plain and rich text formats, PDF documents, markup languages, and metadata for many common file formats. Additionally, <strong>Spotlight</strong> can index multimedia files, system fonts and scripts, and applicationspecific text such as e-mail messages, address book entries, etc. Additionally, <strong>Spotlight</strong> plugins permit developers to expand <strong>Spotlight</strong>’s indexing coverage to handle less common or newly developed text languages and file formats.
Smith 19 Query language and operations <strong>Spotlight</strong>’s query functions are responsible for many of the system’s limitations. It permits basic single-word or multiple-word queries on both text content and syntax (metadata), and its internal division of words into letters allows matching on partial words. Without an understanding of Unix command-line operations, however, users are unable to execute even the simplest of Boolean queries, and cannot specify context queries such as phrase or proximity searches. Apple either considers such querying to be beyond the understanding of most users, or plans to release expanded search functionality in subsequent operating system releases. Regardless of the reason, sophisticated querying is currently only available to ‘power users’. These query limitations are particularly troublesome because: 1. They are not transparent to the user. Internet surfers who use basic Boolean operations such as AND, OR, and “phrase queries” may attempt to execute Boolean operations, and fail to correctly evaluate the results set, as demonstrated by User 2 during the retrieval evaluation (see Query 3). The <strong>Spotlight</strong> interface provides the user with no visual affordances as to proper (or improper) query formulation. 2. Language is a rich communication medium, offering a seemingly boundless diversity of ways in which concepts can be expressed. As a full-text indexing system with no apparent text normalization, <strong>Spotlight</strong>’s information retrieval performance is particularly susceptible to the problems of synonymy and polysemy, and thus particularly in need of sophisticated query operations. The “Virginia” retrieval task (Query 1) used in this paper’s retrieval performance evaluation demonstrates this aptly. User interface, retrieval issues <strong>Spotlight</strong> offers a ‘Smart Folder’ feature, permitting structural queries via a series of dropdown menu choices that can be saved for future use. This interface was found to be stilted, limiting in options, and failing in its support of essential query operations such as phrase searching, Boolean OR statements, etc. Smart Folders are envisioned as a means for users to access their files without regard to their physical storage location. Once a Smart Folder is defined and saved, it updates itself automatically, providing the user with an up-to-date list of all files meeting their specified criteria. Instead of browsing multiple times through layers of nested folders, users can potentially access all relevant information via a single, ‘virtual folder’. The Wall Street Journal rightly points out the potential for this model to change users’ primary mode of information retrieval: “This is a big deal…<strong>Spotlight</strong> could spark a major change in the way people use computers. Instead of hunting for documents or clicking on programs, people may now start activities by searching for relevant files and then opening them as needed” (Mossberg, 2005).
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Page 21: Smith 21 BIBLIOGRAPHY Apple Compute

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