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# Fuzzy logic(Posted on 2007/09/05, 18:56:35)

**Fuzzy logic**is derived from fuzzy set theory dealing with reasoning that is approximate rather than precisely deduced from classical predicate logic. It can be thought of as the application side of fuzzy set theory dealing with well thought out real world expert values for a complex problem (Klir 1997).

Degrees of truth are often confused with probabilities. However, they are conceptually distinct; fuzzy truth represents membership in vaguely defined sets, not likelihood of some event or condition. For example, if a 100-ml glass contains 30 ml of water, then, for two fuzzy sets, Empty and Full, one might define the glass as being 0.7 empty and 0.3 full. Note that the concept of emptiness would be subjective and thus would depend on the observer or designer. Another designer might equally well design a set membership function where the glass would be considered full for all values down to 50 ml. A probabilistic setting would first define a scalar variable for the fullness of the glass, and second, conditional distributions describing the probability that someone would call the glass full given a specific fullness level. Note that the conditioning can be achieved by having a specific observer that randomly selects the label for the glass, a distribution over deterministic observers, or both. While fuzzy logic avoids talking about randomness in this context, this simplification at the same time obscures what is exactly meant by the statement the 'glass is 0.3 full'.

Fuzzy logic allows for set membership values to range (inclusively) between 0 and 1, and in its linguistic form, imprecise concepts like "slightly", "quite" and "very". Specifically, it allows partial membership in a set. It is related to fuzzy sets and possibility theory. It was introduced in 1965 by Lotfi Zadeh at the University of California, Berkeley.

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### Tags

programming, logic, fuzzy, fuzzy logic## Comments

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- sdfds:
- Posted on 2010/08/07, 11:02:48
- " asda "
- sdfds:
- Posted on 2010/08/07, 11:02:43
- " asda dadad "
- sdfds:
- Posted on 2010/08/07, 11:02:37
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- sdfds:
- Posted on 2010/08/07, 11:02:34
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- sdfds:
- Posted on 2010/08/07, 11:02:30
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- majid:
- Posted on 2009/03/11, 08:35:42
- " very nice "
- hamid :
- Posted on 2009/02/09, 11:24:40
- " hamid "
- Azadeh:
- Posted on 2009/01/31, 16:12:37
- " sitetoon vaghan jalebe.tnx "
- n3o:
- Posted on 2009/01/26, 13:40:26
- " elmira - - - - - mishe rabetasho ba emotional learning begi? khoshhal misham bedoonam! "
- mehdi:
- Posted on 2008/07/17, 23:41:07
- " salam "
- elmira:
- Posted on 2008/05/05, 10:36:43
- " ta hala matlabi darmorede rabete fazi ba emotional learinig didid? ertebat inha baham ro midoonid ? "
- ff:
- Posted on 2008/01/24, 04:32:06
- " سلام خسته نباشید واقعا عالیه سایتتون ببخشید سوالی داشتم اگه ممکنه نحوه استفاده کاملشون میشه زحمت بکشید بگید "
- rez a kohan:
- Posted on 2007/11/21, 13:13:46
- " reza kohan ba id tala_kohan "