6 ms·

Fuzzy Logic

86 points by YungSven 7y ago

dang 7y ago
A small related thread from 2011: https://news.ycombinator.com/item?id=2134735 https://news.ycombinator.com/item?id=2134735 Others?
nprescott 7y ago
Just earlier today I was reading through a lab available as part of the J programming language distribution covering fuzzy logic. I'm sure I've read the Wikipedia page for fuzzy logic but the lab really helped to drive home some of the concepts. Additionally, it was a very cool application for J, which is often derided as being a strictly numerical tool. The lab describes itself as: ... how to create a linguistic inference system using fuzzy sets. Such systems of linguistic variables are referred to as fuzzy logic systems. First we describe the concept of membership with nonfuzzy and fuzzy sets. Then we tackle fuzzy membership for scalar and array fuzzy sets, and later inference with array sets. It really is better to work through the lab within the J system[0], but for those without it is browse-able in plain text online[1] [0]: Help -> Studio -> Labs -> General Interest / Fuzzy Logic [1]: https://github.com/jsoftware/labs_labs/blob/master/general/fuzzy.ijt https://github.com/jsoftware/labs_labs/blob/master/general/f...
- kinow 7y ago
  Looks interesting! Haven't heard about J before. I only knew Matlab toolbox for fuzzy sets/logic, and a C and another Java libraries. Shame GitHub syntax hightlight doesn't seem to work well with J files. Will check out the project and try to learn more about it, thanks!
mooze 7y ago
A great application of this in real life is rice cookers.
- kinow 7y ago
  I think washings machines, some digital cameras, and also a train station system in Japan were some other famous applications (from what I can remember).
  - jacques_chester 7y ago
    Automatic gearboxes, ABS, cruise control, some plant controls. Fuzziness saw strongest uptake in Japan, so any control system developed there has a decent chance of having a fuzzy system at its core.
- ragebol 7y ago
  How so?
kinow 7y ago
Small community, with few readers, but still gets some links submitted every now and then: https://www.reddit.com/r/fuzzylogic/ https://www.reddit.com/r/fuzzylogic/
tehsauce 7y ago
"Fuzzy logic is a form of many-valued logic in which the truth values of variables may be any real number between 0 and 1 both inclusive. It is employed to handle the concept of partial truth, where the truth value may range between completely true and completely false." Can someone explain how this is different than bayesian statistics?
- js8 7y ago
  Bayesian statistics is one approach to modelling fuzziness and uncertainty, but fuzzy logic explores other approaches. For example, see https://en.wikipedia.org/wiki/Possibility_theory https://en.wikipedia.org/wiki/Possibility_theory Also fuzzy logic builds a "traditional" logical framework for deduction on terms, again this is a bit different from Bayesian approach, which is more abductive reasoning.
  - tr352 7y ago
    Apart from the other answers, there is also one important technical difference. Fuzzy logic is truth functional but probability is not. That is, in fuzzy logic, if you know the fuzzy truth value of A and of B, you can calculate the fuzzy truth value of “A and B” “A or B” and so on. Not in probability. If you know, let’s say, A and B both have probably 0.9, you don’t know enough to calculate the probability of “A and B”, which lies somewhere between 0.8 and 0.9, or “ A or B”, which lies between 0.9 and 1.
    - elcomet 7y ago
      Yeah but in the real world it doesn't matter does it? you cannot compute the probability A and B for a reason: they might be related (what if they're mutually exclusive for instance? ) So how does fuzzy logic deals with this?
      - tr352 7y ago
        Fuzzy logic deals with this in the exact same way as classical logic. Note that in classical logic, the truth value of "A and B" and "A or B" is also a function of the truth values of A and of B. When using fuzzy logic you have to make a choice as to which function you use. Typically these functions generalise the classical logic ones in the sense that they behave like the classical ones when using 0 and 1. These functions are defined by a so called T-norm.
jblazevic 7y ago
A team I was a part of at the uni made a fuzzy logic-based robot for a soft computing course, almost 20 years ago it seems. I rember that we were able to accomplish seemingly complex behavior (light tracking with obstacle avoidance) with only a few very simple fuzzy logic rules. Seems the project page is still up, along with the source code, schematics and documentation (in Croatian): http://www.zemris.fer.hr/predmeti/nenr/ http://www.zemris.fer.hr/predmeti/nenr/
pjbk 7y ago
Back in the 90s when neural networks and fuzzy logic were the rage and were going to solve all problems of human mankind (déjà vu?), I stumbled upon this nice course put together by Texas A&M in the form of an "ebook" (aka Win3.1 application). Lofti Zadeh himself was a contributor. I looked it up in my bookmarks and I cannot believe that the site is still up: http://faculty.petra.ac.id/resmana/private/fuzzy http://faculty.petra.ac.id/resmana/private/fuzzy I was very interested in training neural networks to find out optimal fuzzy parameters for robotic control systems as an alternative to gain scheduling. There were some cool small companies making nifty scientific apps that I remember evaluating (Aptronix and Neuralogix come to my mind).
- badsectoracula 7y ago
  Out of curiosity i downloaded and downloaded the tutorial and it looks to be more of a hyperlinked multimedia(ish) application, similar to something you'd see made in Hypercard (which makes sense since it seems to be made in ToolBook which essentially was a Hypercard clone for Windows 3.1) and less of something like a PDF, something you'd see in an Amazon Kindle or something you'd see as an EPUB (which is what i think most people would associate with ebooks nowadays). I made a quick capture under VBox with Windows 3.1 for others to see, (though i think it should also work under Wine and otya128's winevdm port to Windows 10): http://runtimeterror.com/pages/badsector/nyan/gimme/webm/fuzzylogicwin31tutorial.webm http://runtimeterror.com/pages/badsector/nyan/gimme/webm/fuz... EDIT: i started reading it now for real and i have to say it is a very interesting way to teach. In theory the hyperlinked approach would work fine in the web, but i cannot think of anything similar in practice. The closest i can think of was some interactive examples in a blog post i found some years ago about making a 2D game.
  - aasasd 7y ago
    I've seen stuff like that back in the early- to mid-2000s. It seems, of course, that most of such ‘multimedia programs’ were educational packages for kids. But most of all, this reminds me of PowerPoint presentations, which iirc were sometimes similarly made for use at home and with educational content. Also olde .HLP and .CHM ‘books’ were employed in this vein.
protomyth 7y ago
Fuzzy Logic and it's rules are pretty amazing for solving problems. I had a lot of fun solving a heating problem with it. Fuzzy Control Language goes with it https://en.m.wikipedia.org/wiki/Fuzzy_Control_Language https://en.m.wikipedia.org/wiki/Fuzzy_Control_Language
airbreather 7y ago
I built a fuzzy logic controller for a very large sag mill in a gold plant (top ten in the world by size). But at the end of it managed to reduce it to a one line formula I could get almost identical results from when simulating in Excel. I don't think this is an unusual case looking at other examples I found on the net - really it is just a form of non linear control and probably the easiest way to deal with a second order system that reverses action over the peak.
sacado2 7y ago
Since we're talking about non-classical logics, I also like modal logic, which deals with uncertainty too, but in a very different way. Here, facts / assertions are not associated with a numeric value, but with a modality, a symbol, meaning "it is possible that F is true", "it is not necessary that F is true", "F is usually true", "F was true yesterday", or "I know I don't know whether F is true or false". https://en.wikipedia.org/wiki/Modal_logic https://en.wikipedia.org/wiki/Modal_logic It has interesting properties, and it avoids the main pitfal of fuzzy logic IMO: when a fact is associated with a truth value of 0.8, what does that really mean? Why is the truth value 0.8 rather than 0.81, for instance? Can we say so for sure?
- jacques_chester 7y ago
  The truth value being 0.8 can be mapped to one or more fuzzy sets. That's what you're typically doing. Saying "I don't know" is still possible, because you can define a fuzzy set representing "I don't know". But now you can say how strongly you don't know. An overlapping alternative is Dempster-Shafer evidence theory, which has "belief functions" and rules on how to combine them.
joeberon 7y ago
What is the difference between fuzzy logic and control theory?
- AstralStorm 7y ago
  First is a tool, the latter is a field of science.
TopHand 7y ago
In the 1990's Bob Pease did a series of articles discussing fuzzy logic and how it compared to conventional control systems, here is a link to the first column. https://www.electronicdesign.com/technologies/digital-ics/article/21757343/whats-all-this-fuzzy-logic-stuff-anyhow https://www.electronicdesign.com/technologies/digital-ics/ar...
eternalban 7y ago
Bart Kosko had some interesting results with Fuzzy: https://en.wikipedia.org/wiki/Bart_Kosko#References https://en.wikipedia.org/wiki/Bart_Kosko#References
tabtab 7y ago
Kind of reminds me of "factor tables", AKA, "fuzzy query-by-example": https://github.com/RowColz/AI https://github.com/RowColz/AI

86 points by YungSven 7y ago

dang 7y ago

A small related thread from 2011: https://news.ycombinator.com/item?id=2134735 https://news.ycombinator.com/item?id=2134735 Others?

nprescott 7y ago

Just earlier today I was reading through a lab available as part of the J programming language distribution covering fuzzy logic. I'm sure I've read the Wikipedia page for fuzzy logic but the lab really helped to drive home some of the concepts. Additionally, it was a very cool application for J, which is often derided as being a strictly numerical tool. The lab describes itself as: ... how to create a linguistic inference system using fuzzy sets. Such systems of linguistic variables are referred to as fuzzy logic systems. First we describe the concept of membership with nonfuzzy and fuzzy sets. Then we tackle fuzzy membership for scalar and array fuzzy sets, and later inference with array sets. It really is better to work through the lab within the J system[0], but for those without it is browse-able in plain text online[1] [0]: Help -> Studio -> Labs -> General Interest / Fuzzy Logic [1]: https://github.com/jsoftware/labs_labs/blob/master/general/fuzzy.ijt https://github.com/jsoftware/labs_labs/blob/master/general/f...

kinow 7y ago
Looks interesting! Haven't heard about J before. I only knew Matlab toolbox for fuzzy sets/logic, and a C and another Java libraries. Shame GitHub syntax hightlight doesn't seem to work well with J files. Will check out the project and try to learn more about it, thanks!

mooze 7y ago

A great application of this in real life is rice cookers.

kinow 7y ago
I think washings machines, some digital cameras, and also a train station system in Japan were some other famous applications (from what I can remember).
- jacques_chester 7y ago
  Automatic gearboxes, ABS, cruise control, some plant controls. Fuzziness saw strongest uptake in Japan, so any control system developed there has a decent chance of having a fuzzy system at its core.
ragebol 7y ago
How so?

kinow 7y ago

Small community, with few readers, but still gets some links submitted every now and then: https://www.reddit.com/r/fuzzylogic/ https://www.reddit.com/r/fuzzylogic/

tehsauce 7y ago

"Fuzzy logic is a form of many-valued logic in which the truth values of variables may be any real number between 0 and 1 both inclusive. It is employed to handle the concept of partial truth, where the truth value may range between completely true and completely false." Can someone explain how this is different than bayesian statistics?

js8 7y ago
Bayesian statistics is one approach to modelling fuzziness and uncertainty, but fuzzy logic explores other approaches. For example, see https://en.wikipedia.org/wiki/Possibility_theory https://en.wikipedia.org/wiki/Possibility_theory Also fuzzy logic builds a "traditional" logical framework for deduction on terms, again this is a bit different from Bayesian approach, which is more abductive reasoning.
- tr352 7y ago
  Apart from the other answers, there is also one important technical difference. Fuzzy logic is truth functional but probability is not. That is, in fuzzy logic, if you know the fuzzy truth value of A and of B, you can calculate the fuzzy truth value of “A and B” “A or B” and so on. Not in probability. If you know, let’s say, A and B both have probably 0.9, you don’t know enough to calculate the probability of “A and B”, which lies somewhere between 0.8 and 0.9, or “ A or B”, which lies between 0.9 and 1.
  - elcomet 7y ago
    Yeah but in the real world it doesn't matter does it? you cannot compute the probability A and B for a reason: they might be related (what if they're mutually exclusive for instance? ) So how does fuzzy logic deals with this?
    - tr352 7y ago
      Fuzzy logic deals with this in the exact same way as classical logic. Note that in classical logic, the truth value of "A and B" and "A or B" is also a function of the truth values of A and of B. When using fuzzy logic you have to make a choice as to which function you use. Typically these functions generalise the classical logic ones in the sense that they behave like the classical ones when using 0 and 1. These functions are defined by a so called T-norm.

jblazevic 7y ago

A team I was a part of at the uni made a fuzzy logic-based robot for a soft computing course, almost 20 years ago it seems. I rember that we were able to accomplish seemingly complex behavior (light tracking with obstacle avoidance) with only a few very simple fuzzy logic rules. Seems the project page is still up, along with the source code, schematics and documentation (in Croatian): http://www.zemris.fer.hr/predmeti/nenr/ http://www.zemris.fer.hr/predmeti/nenr/

pjbk 7y ago

Back in the 90s when neural networks and fuzzy logic were the rage and were going to solve all problems of human mankind (déjà vu?), I stumbled upon this nice course put together by Texas A&M in the form of an "ebook" (aka Win3.1 application). Lofti Zadeh himself was a contributor. I looked it up in my bookmarks and I cannot believe that the site is still up: http://faculty.petra.ac.id/resmana/private/fuzzy http://faculty.petra.ac.id/resmana/private/fuzzy I was very interested in training neural networks to find out optimal fuzzy parameters for robotic control systems as an alternative to gain scheduling. There were some cool small companies making nifty scientific apps that I remember evaluating (Aptronix and Neuralogix come to my mind).

badsectoracula 7y ago
Out of curiosity i downloaded and downloaded the tutorial and it looks to be more of a hyperlinked multimedia(ish) application, similar to something you'd see made in Hypercard (which makes sense since it seems to be made in ToolBook which essentially was a Hypercard clone for Windows 3.1) and less of something like a PDF, something you'd see in an Amazon Kindle or something you'd see as an EPUB (which is what i think most people would associate with ebooks nowadays). I made a quick capture under VBox with Windows 3.1 for others to see, (though i think it should also work under Wine and otya128's winevdm port to Windows 10): http://runtimeterror.com/pages/badsector/nyan/gimme/webm/fuzzylogicwin31tutorial.webm http://runtimeterror.com/pages/badsector/nyan/gimme/webm/fuz... EDIT: i started reading it now for real and i have to say it is a very interesting way to teach. In theory the hyperlinked approach would work fine in the web, but i cannot think of anything similar in practice. The closest i can think of was some interactive examples in a blog post i found some years ago about making a 2D game.
- aasasd 7y ago
  I've seen stuff like that back in the early- to mid-2000s. It seems, of course, that most of such ‘multimedia programs’ were educational packages for kids. But most of all, this reminds me of PowerPoint presentations, which iirc were sometimes similarly made for use at home and with educational content. Also olde .HLP and .CHM ‘books’ were employed in this vein.

protomyth 7y ago

Fuzzy Logic and it's rules are pretty amazing for solving problems. I had a lot of fun solving a heating problem with it. Fuzzy Control Language goes with it https://en.m.wikipedia.org/wiki/Fuzzy_Control_Language https://en.m.wikipedia.org/wiki/Fuzzy_Control_Language

airbreather 7y ago

I built a fuzzy logic controller for a very large sag mill in a gold plant (top ten in the world by size). But at the end of it managed to reduce it to a one line formula I could get almost identical results from when simulating in Excel. I don't think this is an unusual case looking at other examples I found on the net - really it is just a form of non linear control and probably the easiest way to deal with a second order system that reverses action over the peak.

sacado2 7y ago

Since we're talking about non-classical logics, I also like modal logic, which deals with uncertainty too, but in a very different way. Here, facts / assertions are not associated with a numeric value, but with a modality, a symbol, meaning "it is possible that F is true", "it is not necessary that F is true", "F is usually true", "F was true yesterday", or "I know I don't know whether F is true or false". https://en.wikipedia.org/wiki/Modal_logic https://en.wikipedia.org/wiki/Modal_logic It has interesting properties, and it avoids the main pitfal of fuzzy logic IMO: when a fact is associated with a truth value of 0.8, what does that really mean? Why is the truth value 0.8 rather than 0.81, for instance? Can we say so for sure?

jacques_chester 7y ago
The truth value being 0.8 can be mapped to one or more fuzzy sets. That's what you're typically doing. Saying "I don't know" is still possible, because you can define a fuzzy set representing "I don't know". But now you can say how strongly you don't know. An overlapping alternative is Dempster-Shafer evidence theory, which has "belief functions" and rules on how to combine them.

joeberon 7y ago

What is the difference between fuzzy logic and control theory?

AstralStorm 7y ago
First is a tool, the latter is a field of science.

TopHand 7y ago

In the 1990's Bob Pease did a series of articles discussing fuzzy logic and how it compared to conventional control systems, here is a link to the first column. https://www.electronicdesign.com/technologies/digital-ics/article/21757343/whats-all-this-fuzzy-logic-stuff-anyhow https://www.electronicdesign.com/technologies/digital-ics/ar...

eternalban 7y ago

Bart Kosko had some interesting results with Fuzzy: https://en.wikipedia.org/wiki/Bart_Kosko#References https://en.wikipedia.org/wiki/Bart_Kosko#References

tabtab 7y ago

Kind of reminds me of "factor tables", AKA, "fuzzy query-by-example": https://github.com/RowColz/AI https://github.com/RowColz/AI