Modern Information Retrieval Chapter 10: User Interfaces and Visualization

Contents

      
2. From Command Lines to Forms and Menus

Boolean query specification!command line syntax

Aside from conceptual misunderstandings of the logical meaning of AND and OR, another part of the problem with pure Boolean query specification in online bibliographic systems is the arbitrariness of the syntax and the contextlessness nature of the TTY-based interface in which they are predominantly available. Typically input is typed at a prompt and is of a form something like the following:

COMMAND ATTRIBUTE value {BOOLEAN-OPERATOR ATTRIBUTE value}*
e.g.,
FIND PA darwin AND TW species OR TW descent
or
FIND TW Mt St. Helens AND DATE 1981

(These examples are derived from the syntax of the telnet interface to the University of California Melvyl system  [#!lync92!#].) The user must remember the commands and attribute names, which are easily forgotten between usages of the system [#!meadow89!#]. Compounding this problem, despite the fact that the command languages for the two main online bibliographic systems at UC Berkeley have different but very similar syntaxes, after more than ten years one of the systems still reports an error if the author field is specified as PA instead of PN, as is done in the other system. This lack of flexibility in the syntax is characteristic of interfaces designed to suit the system rather than its users.

Boolean query specification!Melvyl Boolean query specification!form fillin Melvyl system form fillin

The new Web-based version of Melvyl provides form fillin and menu selection so the user no longer has to remember the names and types of attributes available. Users select metadata types from listboxes and attributes are shown explicitly, allowing selection as an alternative to specification. For example, the `search type' field is adjacent to an entry form in which users can enter keywords, and a choice between AND and NOT is provided adjacent to a list of the available document types (editorial, feature, etc.). Only the metadata associated with a given collection is shown in the context of search over that collection. (Unfortunately the system is restricted to searching over only one database at a time. It does however provide a mechanism for applying a previously executed search to a new database.) See Figure .

  

Figure: A view of query specification in the Web-based version of the Melvylbibliographic catalog. Copyright © 1998, The Regents of the University of California.

The Web-based version of Melvyl also allows retention of context between searches, storing prior results in tables and hyperlinking these results to lists containing the retrieved bibliographic information. Users can also modify any of the previously submitted queries by selecting a checkbox beside the record of the query. The graphical display makes explicit and immediate many of the powerful options of the system that most users would not learn using the command-line version of the interface.

Bit-mapped displays are an improvement over command-line interface, but do not solve all the problems. For example, a blank entry form is in some ways not much better than a TTY prompt, because it does not provide the user with clues about what kinds of terms should be entered.