some essential definitions

some essential definitions in the field of cryptography are:
- cryptoanalysis
- cryptology
- ciphers

"Few false ideas have more firmly gripped the minds of so many intelligent men than the one that, if they just tried, they could invent a cipher that no one could break." (David Kahn)

codes
plaintext
ciphertext
to encipher/encode
to decipher/decode

The variants of encryption systems are endless.
For deciphering there exists always the same game of trial and error (first guessing the encryption method, then the code). A help to do so is pruning. Once, after a more or less long or short period a code/cipher breaks. Monoalphabetic ciphers can be broken easily and of course are no longer used today but for games.

for further information on codes and ciphers etc. see:
http://www.optonline.com/comptons/ceo/01004A.html
http://www.ridex.co.uk/cryptology/#_Toc439908851

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Artificial Intelligence

Artificial Intelligence is concerned with the simulation of human thinking and emotions in information technology. AI develops "intelligent systems" capable, for example, of learning and logical deduction. AI systems are used for creatively handling large amounts of data (as in data mining), as well as in natural speech processing and image recognition. AI is also used as to support decision taking in highly complex environments.
Yahoo AI sites: http://dir.yahoo.com/Science/Computer_Science/Artificial_Intelligence/
MIT AI lab: http://www.ai.mit.edu/


http://dir.yahoo.com/Science/Computer_Science...
http://www.ai.mit.edu/
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Expert system

Expert systems are advanced computer programs that mimic the knowledge and reasoning capabilities of an expert in a particular discipline. Their creators strive to clone the expertise of one or several human specialists to develop a tool that can be used by the layman to solve difficult or ambiguous problems. Expert systems differ from conventional computer programs as they combine facts with rules that state relations between the facts to achieve a crude form of reasoning analogous to artificial intelligence. The three main elements of expert systems are: (1) an interface which allows interaction between the system and the user, (2) a database (also called the knowledge base) which consists of axioms and rules, and (3) the inference engine, a computer program that executes the inference-making process. The disadvantage of rule-based expert systems is that they cannot handle unanticipated events, as every condition that may be encountered must be described by a rule. They also remain limited to narrow problem domains such as troubleshooting malfunctioning equipment or medical image interpretation, but still have the advantage of being much lower in costs compared with paying an expert or a team of specialists.

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