A CDE Definition
A search for data that meets several criteria by using the Boolean operators AND, OR and NOT (see Boolean logic). For example, the request: "Search for all Spanish and French speaking employees who have MBAs" would be written as follows if the query were expressed on a command line. Spanish and French are placed in parentheses in order to be treated as a single item.
list for degree="MBA" and
(language="Spanish" or language="French")
In the following example, the parentheses are missing, and the query is incorrect. The AND ties MBA and Spanish together; therefore, people who speak Spanish and have an MBA would be selected, which is correct. However, the OR separates French from the rest of the query, and anyone speaking French, no matter which degree they held, would also be selected.
list for degree="MBA" and
language="Spanish" or language="French"
A Google "Advanced" (Boolean) Search
The "mathematics of logic," developed by English mathematician George Boole in the mid-19th century. Its rules govern logical functions (true/false) and are the foundation of all electronic circuits in the computer. As add, subtract, multiply and divide are the primary operations of arithmetic, AND, OR and NOT are the primary operations of Boolean logic. Boolean logic is turned into logic gates on the chip, and the logic gates make up logic circuits that perform functions such as how to add two numbers together.
Various permutations of AND, OR and NOT are used, including NAND, NOR, XOR and XNOR. The rules, or truth tables, for AND, OR and NOT follow. See Boolean search, binary, logic gate and Bebop to the Boolean Boogie.
Curious About the Chip?Wired in patterns of Boolean logic and in less space than a postage stamp, transistors in one of today's high-speed chips collectively open and close quadrillions of times every second. If you are curious about how it really works down deep in the layers of the silicon, read the rest of "Boolean logic," then "chip" and, finally, "transistor." It is a fascinating venture into a microscopic world.
The following AND, OR and NOT examples use mechanical switches to show open and closed transistors. The switching part of an actual transistor is solid state (see transistor).
An AND Gate (Wired in Series)
An OR Gate (Wired in Parallel)
A NOT Gate (Input Is Reversed)
Adding Two Bits Together
The Half-Adder Circuit
Try It Yourself
Before/After Your Search Term
|Boole & Babbage||Boomerang|
|Boolean algebra||Boot Camp|
|Boolean circuit||boot disk|
|Boolean data||boot drive|
|Boolean expression||boot failure|
|Boolean logic||boot loader|
|Boolean operator||boot manager|
|Boolean query||boot order|
Terms By Topic
Click any of the following categories for a list of fundamental terms.