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Don't mind my grammar or sense of humor & my over use of Bolding & Italics Please :)
Anyway, Here is the Long and the short of it:
Lets go boolean!
One day a friend of mine came over to look for
a place to buy worms, he wants to start a fishing shop here in Newnan. He
sits down at my computer goes to snap.com and types in "worms" :>) and
it gives him 32,000 web sites, I was doing something and I didn't catch him
right away, about 1 hour later he says forget it I cant find anything, just
a lot of Reports, Stories, Gov. Tests and dumb stuff.
So I did it for him to show him how Boolean
Searching works, I also used snap.com but I put in some other words: Worms,
bait, and it came back with a few hundred matches, so I also added: wholesaler
and tackle that brought it down to ten good hits, and they were all what he
was looking for.
I do so much researching for info, I use this almost every day to find a company or product and
for product info, I buy things that look cool at Estate sales or Auctions
and sometimes I don't even know what it is till I get it home and do a search,
one time I bought an Ele. item because it was neat? :) on the bottom it
had a company and a model number, I put both into the search and it gave
me one (1) web site, a Gov. site on old Navy equipment and told me everything
I needed to know.
The term" Boolean," often encountered when doing searches on the Web, refers to
a system of logical thought developed by and Named after the nineteenth-century
English mathematician and computer pioneer, George
Boole (1815-64). Boolean Logic is a form of algebra
in which all values are reduced to either TRUE or FALSE.
What's so logical about Boolean algebra? :>)
George Boole
believed in what he called the "process of analysis", that is, the process by which combinations of interpretable symbols
are obtained. It is the use of these symbols according to well-determined
methods of combination that he believed presented "true calculus".
Today, all of our computers employ Boole's
logic system - using microchips that contain thousands of tiny electronic
switches arranged into logical "gates" that produce predictable and reliable
conclusions.
The basic logic gates comprise of AND, OR and NOT.
It is these gates, used in differing combinations, that allow the computer
to execute its operations using binary language.
Each gate assesses various information (consisting
of high or low voltages) in accordance with predetermined rules, and produces
a single high or low voltage logical conclusion. The voltage itself represents
the binary yes-no, true-false, one-zero concept.
Boolean logic is especially important for
computer science because it fits nicely with the binary numbering system,
in which each bit has a value of either 1 or 0. Another way of looking at
it is that each bit has a value of either TRUE or FALSE.
In Boolean searching, an "and" operator between
two words or other values (for example, "pear AND apple") means one is searching for documents containing both
of the words or values, not just one of them. An "or" operator between two
words or other values (for example, "pear OR apple") means one is searching for documents containing either
of the words.
In computer operation with binary values, Boolean
logic can be used to describe electro magnetically charged memory
locations or circuit states that are either charged (1 or true) or not charged
(0 or false). The computer can use an AND gate or an OR gate operation to obtain a result that can be used for further
processing. The following table shows the results from applying AND and OR operations to two compared states:
AND, OR, XOR, NOT ( 0 n? 0 = 0 )
If you'd like to refine your searching,
you can include the Boolean operators AND, OR, and
NOT in your search.
For example, if you're looking for products by Dell and Gateway, simply type
"Dell OR Gateway" (no quotes) in the Quick Search box. This search will produce
listings for both manufacturers.
The technique for combining keywords to broaden
or narrow your search in databases is called Boolean searching. The terms
you can use to combine keywords are called Boolean operators. The three most
common operators are "and," "or,"
and "adj" (which stands for "adjacent").
And Placing the term "and" between two or more
keywords narrows your search. "And" tells your database to retrieve books
and articles whose database records contain all the keywords you enter.
Or Placing the term "or" between two or
more keywords broadens your search. "Or" tells your database to retrieve
books and articles whose database records contain at least one of the keywords
you enter.
Adj Placing the term "adj" between two or
more keywords tells your database to retrieve books and articles whose database
records contain your keywords in the exact order you enter them.
Every database has a different, automatic method
of interpreting and then searching for the keywords you type in. This automatic
operation is called the database's default. Each database has its own default
method of operation.
Some databases automatically combine any
two keywords with "adj." Others may use "and" or "or." Unless you use the Boolean
operators to specify otherwise, the database will revert to its default.
Some automatically truncate your words.
Truncation is a procedure where databases automatically look for different
endings for the same keyword.
Some databases search only titles for your
keywords, while others may search subject terms or summary paragraphs (abstracts).
Your database will operate by its default unless you specify otherwise. To
figure out just how a database will operate, check the database's own help
screens or ask a librarian. Remember that although databases may look and
act differently, the basic principle is still the same. Sometimes you can
just enter it as "worms bait wholesaler tackle" because of default operators,
(that is how I search), it may even come back with 50,000 hits, but because all of your
words are Priority. (what you are looking for will
be in the first ten or so....)
Once you have mastered Boolean keyword searching,
you will be able to use any database.
Boolean operators,
- NOT: NOT X is 0 if X is 1, is 1 otherwise
- AND: X AND Y is 1 if X and Y are 1, is 0 otherwise
- NAND: X NAND Y is 0 if X and Y are 1, is 1 otherwise
- OR: X OR Y is 0 if X and Y are 0, is 1 otherwise
- NOR: X NOR Y is 1 if X and Y are 0, is 0 otherwise
- XOR: X XOR Y is 0 if X and Y are the same, is
1 otherwise
- XNOR: X XNOR Y is 1 if X and Y are the same,
is 0 otherwise
Evaluating Boolean expressions
As with arithmetic equations, complex Boolean
expressions can be obtained by combining operators and operands, with precedence
shown using brackets:
- X AND Y
- X OR (X AND Y)
- NOT (X OR (X AND Y))
As notational shorthand, we often write
- X*Y to mean X AND Y
- X + Y to mean X OR Y
- X' to mean NOT X
When evaluating expressions (again, like with arithmetic expressions) start with the simpler values and work your way up to the entire
expression:
Suppose F = (((X' + Y)*(Y*Z)) + Z') and we want
to know F when X = 0, Y = 1, Z = 0
- F = (((X' + Y)*(Y*Z)) + Z')
- = (((0' + 1)*(1*0)) + 0')
- = (((1 + 1)*( 0 )) + 1 )
- = ((( 1 )*( 0 )) + 1 )
- = (( 0 ) + 1 )
- = ( 1 )
Ahh, poop, I really Hate Algebra,
but!
Laws of Boolean algebra
There are a number of axioms of Boolean algebra
that can be used to simplify Boolean formulas.
Some of these are:
- X + 0 = X
- X + X' = 1
- X + X = X
- X + 1 = 1
- (X')' = X
- X + Y = Y + X
- X + (Y + Z) = (X + Y) + Z
- X * (Y + Z) = (X * Y) + (X * Z)
- (X + Y)' = X' * Y'
- X + (X * Y) = X
- X * 1 = X
- X * X' = 0
- X * X = X
- X * 0 = 0
- X * Y = Y * X
- X * (Y * Z) = (X * Y) * Z
- X + (Y * Z) = (X + Y) * (X + Z)
- (X * Y)' = X' + Y'
- X * (X + Y) = X
Using the "and" Boolean operator, (this is one more way of looking at and)
The "and" Boolean operator tells your database
to retrieve materials whose database records contain all the keywords you
select. This allows you to narrow the focus of your search by eliminating
the books and articles that do not contain all the keywords you enter.
For example:
Research topic: effects of advertising on children
Keyword search: advertising and children
Using "and" will tell your
database to look for citations that include both concepts: "advertising"
and "children."
Another example:
Research topic: effects of tobacco advertising on children
Keyword search: tobacco and advertising and children
Using "and" will tell your database to look for
citations that include all three concepts: "tobacco," "advertising," and
"children."
Using the "or" Boolean operator (this is one
more way of looking at or)
The "or" Boolean operator tells your database to
retrieve materials whose database records contain any of the keywords you
enter. This allows you to broaden the focus of your search by including
synonyms and related terms.
For example:
Research topic: effects of advertising
Keyword search: advertising or commercials
Using "or" will tell your database to look for
citations that include either of the two concepts: "advertising" or "commercials."
In most databases, using the "and" and "or" Boolean
operators together requires a special procedure. Group "or" keywords
together with parentheses.
For example:
Research topic: effects of advertising on children
Keyword search: (advertising or commercials) and children
Your database will now look for records that
include "children" and either "advertising" or "commercials."
How do I choose the best word for my search.
When you search with keywords, you instruct
your database to retrieve citations to books and articles whose records in
the database contain your keywords. The keywords you decide to use will determine
whether or not you get the best results from your search.
There are several things you should do
to get great results when searching by keywords.
Use words that communicate main topic ideas.
Authors often use many words in their titles that don't really communicate
the main ideas. You should avoid words that don't focus on the central concepts
of your topic.
Avoid words that describe the relationships
between things. Your keywords should clearly identify your research topic.
Some words are unique to your topic--like "cloning" or "advertising." Other
words--like "effects" or "research"--could be used in just about any topic.
Use only words that identify the key concepts in your topic.
Use single words or very short phrases.
Avoid phrases of more than two words. Databases will search their contents
for books and articles that contain the exact words you enter when you conduct
your keyword search. The more consecutive words you string together, the
less chance you have of finding authors that have used the same long phrase
in the titles of their publications.
For example:
a bad example: "effects of birth order on sibling relationships"
a good example: "birth order and sibling"
Use specific subject terms in a subject-specific
database. When you search a specialized database that contains books and articles
on a single subject, don't use that single subject as a search word. For
example, when searching an education database, don't use the word "education"
as a keyword. If you do, you'll probably receive a results list that contains
everything in the database.
Use broader or narrower keywords depending
on the database type. Books tend to cover broad topics. Their titles will
often contain nonspecific, general terms. If you're searching a database that
primarily lists books (like MNCAT), use broad keywords.
Conversely, use specific keywords when
searching articles-only databases. Articles tend to cover specific topics.
Their titles will often contain more specialized, precise terms. If you're
searching a database that primarily lists articles, use more specific keywords.
For example, if you were searching for information
about teaching math to elementary school children, you would search books-only
and articles-only databases in two different ways. In a database of articles,
you might do a search using the words "teaching and elementary and math and
children." In a database of books, you might do a search using the words
"teaching and elementary school."
Use truncation:
Some databases allow you to broaden your
search by retrieving materials that contain different endings for the same
word. For example, you can do a search for all the words that follow below
using a single search term. compose, composed, composition, composer
To retrieve citations that contain any of these
words, search with the root of the word followed by a special symbol. For
example, you might search with compos? or compos*.
This searching technique is called truncation
or wild card searching. Truncation allows you to search a database for books
and articles that contain different forms of your keyword by using a single
command. The command for truncation uses the word root and a special truncation
symbol. This symbol can vary from database to database.
It is important when using truncation,
however, to make sure you choose the best root word for your search.
Why is searching for "com?" a bad idea?
You just have to try all the ways to find what
way works best for you, I find now, I search the same way almost all the
time. (stuck in a rut)
worms (search word) bait (search word) wholesaler
(qualifier word, narrows it down to what I really want)
On the next subject, I could type 20 more pages
on this one:-> how does it know where to go to find what I am looking
for.
Hidden in the HTML code of web sites there
is what is called a META Tag. that contains key words about that web site,
up to one hundred words. And that's the short of it :)
If you want to know more, you can search snap
for:
"html AND meta tag NOT code" :>)
To learn more about Boolean Try some of these sites:
http://www.albany.edu/library/internet/boolean.html
http://adam.ac.uk/info/boolean.html
http://www.math.csusb.edu/notes/sets/boole/boole.html
Really good Search sites I use every day: There
are way to many to list here
I hope this helps, if you need info on something.
If you ever need anything please feel free to call
or E-mail me anytime.
IMPORTANT NOTE: Since this order is radically different from standard database
and programming operations, the use of parentheses to clarify the relationships
between search terms is necessary in every Boolean or field search.
Order of Boolean Operation In Some Search Engines:
1. :fieldname: (Field)
2. ADJ (Adjacency),
3. [blank space] (OR),
4. - (NOT),
5. & (AND),
Boolean Operators
OPERATOR CONDITION
- = EQUAL
- & AND
- - NOT
- BLANK OR
- ADJ ADJACENT
- #W PROXIMITY
- > GREATER THAN
- < LESS THAN
- >= GREATER THAN OR EQUAL TO
- <= LESS THAN OR EQUAL TO
- @ RANGE
- * WILDCARD FOR MULTIPLE CHARACTER
- ? WILDCARD FOR SINGLE CHARACTER
- ( ) PARENTHESES-RESTRICTION
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