Introduction to Search Tools

Tom Kelliher, CS 102

Sept. 7, 1998

Announcements: Accounts?

From last time:

1. Passwords, drives, cleaning house, and windows.

Outline:

1. Introduction to search tools

2. Types of search tools.

3. Hands-on exercise.

Assignment: Read Sections A--E of http://www.ultranet.com/~egrlib/tutor.htm --- How to Search the World Wide Web: A Tutorial for Beginners and Non-Experts. I will post a list of questions on the class home page to guide your study.

Search Tools

1. What is a search tool?

2. Finding the ``Searching the Web'' entry at Yahoo. Bookmark it.

3. The types of search tools:
   1. Directory search tool.
      1. Indexed by subject matter. Like an ``expanding'' table of contents.

      2. Example: LookSmart

      3. Advantage: Subject indices compiled by skilled persons.

      4. Disadvantage: Subject indices not updated frequently and are comparatively small. Commercial influences upon selection?

   2. Search engine.
      1. Accesses databases by using keywords. Aka ``keyword search.'' Like the index in a book. Results in ``hits.''

      2. Example: Altavista

      3. Advantage: Databases are large and updated frequently.

      4. Disadvantage: Keyword searches are often not precise, therefore harder to use.

   3. Combined directory/search engine.
      1. Allows you to switch between the two methods. The deeper in the directory you go, the narrower the field of search for the search engine.

      2. Example: Yahoo

      3. Use when you're not sure if subject or keyword search will work best.

      4. Advantage: Ability to narrow the search area within a keyword search.

      5. Disadvantage: Keyword option may not work well for difficult searches. Keyword searches only search over subject indices.

   4. Multi-Engine.
      1. A so-called meta-search engine that uses a number of other search engines to perform searches.

      2. Example: Metacrawler

      3. Used to speed up the search process.

      4. Advantage: often provides fewer hits and is more tolerant of imprecisely-formed searches.

      5. Disadvantage: Not as effective as a search engine for difficult searches.

4. How do they know what's out there? Spiders and Robots.

5. How do I use one?

   Exercise: Working in groups of two, visit
   http://www.ultranet.com/~egrlib/tutor.htm --- Search Exercise and try the four search exercises at the end of Section A.