Unit 5: Advanced Searching and Boolean Operators

Indexes like Yahoo! are heirarchical tables of contents to the Web. They can also function as search engines by searching with key words. Other search engines are even more powerful programs that can do both basic keyword searches and advanced keyword searches using Boolean operators. We will begin with the basics of Webcrawler searching.



Advanced Searching with Boolean Operators

George Boole (1815-1864), British mathematician and logician, developed Boolean algebra in which symbols are used to denote logical propositions. Boolean algebra has been essential to the development of modern computers. We use these logical concepts in keyword searches, too. In keyword searches the Boolean operators are AND, OR, and NOT. They are used to specify the logical relationship between two or more keywords. They allow you to broaden or narrow your search.

Horse AND Thoroughbred

AND narrows your search to only records containing both terms.

Horse OR Race

OR broadens your search to records containing either or both terms.

Horse NOT Race

NOT restricts your search to the first item.

You can use the Boolean operators AND, OR and NOT in keyword searches both at the Library and on the Internet in Advanced or Custom Searches on many search engines.

1. Go to the following web site to learn more about basic Boolean logic. Print it .

Boolean Searching on the Internet from the University at Albany library

http://www.albany.edu/library/internet/boolean.html

 

 

Alta Vista supports two more operators, NEAR and parentheses ( ). When you use NEAR between two words, it means that those words are found near each other in the records that Alta Vista searches, so they are probably related in some way.

You can use ( ) to group terms you want handled first in the search, ex: (product OR strict) AND liability.

2.  Go to the Advanced Search tutorial on Alta Vista to read about NEAR and parentheses. Then print out the Advanced Search Cheat Sheet (click it at the top of Advanced Search):

http://doc.altavista.com/adv_search/ast_as_index.html

 

Some search engines allow you to group words you want to appear together as a phrase by using quotation marks, ex. "atlantic ocean" NOT "atlantic city." Some search engines use + to include all of the terms and - to omit a term.

  1. Go to IxQuick Metasearch to learn more about quotation marks, + and -, and some other symbols.

http://ixquick.com/eng/power_search_techniques.html

 

A Research Exercise with Boolean Operators

Directions:

Imagine that you are planning to write a research paper on the United Fruit Company.

I. Begin with IxQuick Metasearch http://www.ixquick.com

1. In the search box type in united fruit company.

Results? _________________________

Scroll down to see what you got. Are they all about the United Fruit Company? _____

  1. Now type in "united fruit company."

Results?

Scroll down, click on, and skim some of the results that don't seem to be about the United Fruit Company. Is the United Fruit Company mentioned somewhere in the articles? ________________

(If you have a problem clicking BACK to the results page, type www.ixquick.com and do the search again. Some web pages won't let you go BACK.)

All of the matches to a search phrase in quotation marks will have the phrase somewhere in the text. Then it is your job to decide if the article will be useful or not.

  1. Now go to the AltaVista Search Home Page http://www.altavista.com and do the same search.

1. Type in united fruit company (quotation marks are not necessary in this search engine).

Results? _________________________

Are all the results about the United Fruit Company? _____________________

  1. Now type in united fruit company AND NOT guatemala
  2. What happened?

    This search page does not recognize boolean operators.

  3. Go BACK to the Search Home Page and click Advanced Search.
  4. Now type in united fruit company AND NOT guatemala into the boolean query box.

Choose English and type "united fruit company" in the sort by box.

How many pages were found? _____________________________

This result puts United Fruit Company pages first and others later.

5. Scroll back up to your search and delete sort by "united fruit company."

What happens? _________________________________________

Do these results mention the United Fruit Company first? _____________________

The sort by box is helpful in putting results in a useful order for your research.

 

III. Finally, do a research project of your own.

Use

http://www.AltaVista.com and http://www.ixquick.com

 

  1. Choose a topic and write down some key words. Use the Boolean operators to compose some possible search phrases.
  2.  

     

     

  3. Try your different keyword combinations in the search boxes of the two search engines.
  4. What are your results? If they are not promising, try new key words and combinations. If they look good, take a look at some of them.
  5. If any of your results seem as if they will be useful in the future, you should save the URL.

 

Saving Interesting URL's

As you work on your research, you will want to save the interesting web sites' URLs. One way to save URLs is to write them down, but it's really easy to make mistakes. Here are two safer ways to save.

Bookmarks

On your own computer, you can pull down the "bookmark" menu in Netscape and choose "add bookmark". Later, when you pull down the bookmark menu again, the name of that site will appear. You can choose it, and the browser will automatically connect you to that site again.

On public computers, you will need to save your URL's to a Microsoft Word document. Here is how to do it.

To Open Microsoft Word:

1. Go to the apple menu, go down to programs, then pull down to and choose Microsoft Word. When the program opens, an untitled page will appear. You should type a title on the page: "Interesting URL's" and then save it just as you do when you write a composition.
2. Now you have both a Word document page and Netscape open on the desktop of the computer. You can bring one or the other to the front by clicking on any piece of it you can see. You can move them around on the screen and separate them by holding the cursor arrow on the top line bar and dragging. Separate them now. Then click on the Netscape page to bring it to the front.
3. When you find an interesting site on the web, you will see its URL in the location box at the top of the page. First,we are going to select the URL by highlighting it; then we will "copy" the URL from this page and "paste" it into the Word document.

Copy the URL from an interesting site

4. Click the Netscape page to bring it to the front of the screen. Move the cursor up to the location box, hold the mouse button down and drag the cursor across the URL to highlight it.
5. Pull down the "Edit" menu and choose "copy".

 

Paste the URL into your Word document

6. Now bring the Word document to the front by clicking on any piece of it that you can see.
7. Put your cursor where you want the URL to go on the Word document.
8. Pull down the "Edit" menu and choose "Paste."
9. When the URL appears, click "Save." (At this point it's a good idea to write a brief note to yourself about the URL site so that you will remember what it is later.) Be sure you save to your own diskette.
10. Bring the Netscape page back to the front (click on any part of it) and continue your search.
11. Continue to copy, paste, and save URL's until you are ready to print them out.

 

1. Compare Webcrawler and the indexes Yahoo! , Lycos, Info Seek, and Hot Bot. How are they similar? How are they different? Which would be the most useful to you? Why?

2. What did you learn about Boolean operators? How did they help you?

Write in the space provided on the next page. Then send me your ideas.

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Helen H. Schmidt
Instructor, Intensive English and Orientation Program
Iowa State University, Ames, Iowa 50011, U.S.A.
Email:hschmidt@iastate.edu

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