User talk:LBehounek

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[edit] Welcome

Hey Libor, Looks like you know what you are doing, but usually new users are given "welcome" messages and the like, and I didn't want you to be an exception. Anyway, thanks a lot for all of your help to wikipedia so far. I'm excited seeing all the work you are doing, and to see your to do list on your user page. There are a few mathematicians around, some of whom understand fuzzy logic a little, so don't hesitate to ask if you have any questions. The talk pages at Wikipedia:WikiProject Mathematics are a good place to look for help specific to how wikipedia approaches math. But again, you seem to know whats up. Let me know if you have any questions. And here is a formulaic welcome, just in case you want some links to the basics.

Welcome!

Hello, LBehounek, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are some pages that you might find helpful:

I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you need help, check out Wikipedia:Questions, ask me on my talk page, or place {{helpme}} on your talk page and ask your question there. Again, welcome!  Smmurphy(Talk) 03:34, 19 February 2007 (UTC)

Thank you for welcoming me to Wikipedia, and thanks for your kind words. I've been lurking about for some time (made some 20 smaller edits to English and Czech Wikipedia during the year before my registration), but since Wikipedia has become so immensely useful (esp. after it reached several hundred thousand articles), I feel obliged to contribute more significantly — and I do enjoy it a lot. LBehounek 10:54, 19 February 2007 (UTC)

[edit] capacity =? fuzzy membership function

I'm wondering if you had a definition of a fuzzy membership function handy and could verify that these two things are the same. A capacity in decision theory is simply a function from the set of subsets of some set into [0,1] which is monotone and is normalized (ie \empty \rightarrow 0, \Omega \rightarrow 1). Clearly this is a generalization of a probability measure, where the probability axiom of countability is weakened. Would you say that this is the same as a membership function? I put this into the membership function, so that I could write an article on the Choquet integral. Perhaps there is a fuzzy integral parallel of this. If so, don't hesitate to pitch in or give me a hint where to look. Thanks, Smmurphy(Talk) 03:49, 25 March 2007 (UTC)

A membership function on a set X is just any mapping X → [0, 1]. (The definition in the article on membership functions a bit unclear and I'm going to make a small edit right now to make it clearer; unfortunately I am currently too busy for larger edits which should be made there.) So capacities are a special kind of membership functions (capacities are defined on powersets and must be normalized and monotone; membership functions need not satisfy any of these conditions; often they are not even required to take values in [0, 1], but just in any fixed lattice or poset). In any case, your text on capacities as an important example of membership functions is definitely correct.
Since capacities are special membership functions (on the powerset of Ω), a capacity can be viewed as a fuzzy set of subsets of Ω. Because of this connection to fuzzy sets, capacities are also called fuzzy measures. Wikipedia contains a stub on fuzzy measure theory, which may be a suitable place for some info on capacities (you may consider moving a part of your text there, leaving just one or two sentences with a link in the article on membership functions). -- LBehounek 20:00, 27 March 2007 (UTC)
OK thanks, that makes sense. The leads in both articles are a bit off, then. I guess I'm not going to work on it for a couple days at least, but I'm taking a course in decision theory, and I'll probably try to work on that stuff soon. Do you think that there should be seperate articles for fuzzy measure, fuzzy measure theory, and capacity? Best, Smmurphy(Talk) 04:18, 28 March 2007 (UTC)
Yes, I think it will be good to have three separate articles, after enough contents in which they should differ is written (until then, I'd prefer redirects). But surely the three topics are different, since the agenda of fuzzy measure theory is not just the notion of fuzzy measure itself; and even though capacities coincide with fuzzy measures as mathematical structures, they surely have different motivation, applications, history, references, etc. Looking forward to your edits of capacity-related articles, LBehounek 17:00, 28 March 2007 (UTC)

[edit] Reference for your entry to Indicator function ?

The only reference I know of is Kuzko's rather simple book. Perhaps you know of better one(s) to add to the references. Thanks, wvbaileyWvbailey 21:02, 24 May 2007 (UTC)

I have added two references to the original papers by Zadeh (for [0, 1]-valued fuzzy sets, available online [1]) and Goguen (for lattice-valued fuzzy sets). Currently there are many standard textbooks for fuzzy set theory, each explaining the notion of membership function, but I suppose the original papers are informative enough (at the level of description provided in the WP article). Surely the notion would need a far more extensive explanation (not to be confused with probabilistic distributions etc.), but I know no good references for a concise and well-written exposition. -- Best, LBehounek 21:20, 24 May 2007 (UTC)

[edit] WikiProject Czech Republic

We would like to invite you to join WikiProject Czech Republic, an attempt to build and maintain a large and neutral database of the Czech Republic-related articles on Wikipedia. To join, simply add your name to the members section of WikiProject Czech Republic.

≈Tulkolahten≈≈talk≈ 16:44, 22 October 2007 (UTC)

Thank you very much for inviting me to participate in the project. I consider the project very important, as Czech-related topics are still underrepresented in WP. Unfortunately I am currently so busy with extra-WP matters (so much that I was unable to make any WP edits in Nov 2007) that in the near future I won't be able to contribute to it in any non-trivial way. Nevertheless, I have bookmarked the project page and will check it occasionally (and hopefully continue making small edits in Czech-related articles, if time allows). After my schedule clears up a bit, I'll be happy to join and put myself on the project list. -- LBehounek (talk) 15:02, 11 December 2007 (UTC)

[edit] Hi, Libor

Nice to find here, Libor! I have seen some of your good job. Do you think, when you will have some time of course, that we could collaborate to improve fuzzy-logic-related articles? There is a lot of work to be done (many missing entries), and moreover the main one, fuzzy logic, is quite strange, don't you think? --Cnoguera (talk) 11:08, 26 February 2008 (UTC)

Hi Carles! Sure, I'll be happy if we coordinate our efforts. Indeed, fuzzy logic and several other articles on fuzzy logic are quite strange and should be repaired (or made more balanced). Also some articles in general logic are inaccurate and/or take only classical logic into account: for instance, propositional variable is currently defined as "a variable which is either true or false". The to-do list on my user page collects some changes needed to be made (besides articles I would like to expand), but you can see from the dates that I have too little time to fix all of them soon. So I'll be happy to cooperate on improving (fuzzy-)logic-related articles; we can make some arrangements by email or next time we meet. Best, LBehounek (talk) 15:34, 26 February 2008 (UTC)

Hi again! Based on your nice entry for MTL I have started the article for BL. I will try to complete it and start other entries when I will have more time. It would be really nice to have entries for all the important logics. --Carles Noguera (talk) 12:47, 18 April 2008 (UTC)

Great—this was my intention, too, to create an entry for all important fuzzy logics (basic, Gödel, product, etc.) and expand the existing ones (e.g., Łukasiewicz); but till now I only had time for MTL, some correction and expansion of Łukasiewicz logic, and part of a summary article on t-norm logics (to avoid repetitions regarding common features in the articles on particular logics). I'm glad that you will help me with this task. My current plan is at least to create short stubs on all main fuzzy logics, to avoid red links in other articles, and later expand them; but at present I have too little time even for this. -- LBehounek (talk) 12:20, 20 April 2008 (UTC)

Btw, one question came to my mind regarding this kind of work. Since we are writing entries about our research topic it is likely that we will be in the situation of referring to our own papers. Would this contradict any wikipedia policy? Do you know about it? I was trying to find it, and I could not. --Carles Noguera (talk) 15:45, 18 April 2008 (UTC)

I think the basic guideline for this is Wikipedia:Conflict of interest. Among other things it says: Editing in an area in which you have professional or academic expertise is not, in itself, a conflict of interest. Using material you yourself have written or published is allowed within reason, but only if it is notable and conforms to the content policies. Excessive self-citation is strongly discouraged. When in doubt, defer to the community's opinion. Fortunately, I am in less danger of a conflict of interest myself when writing about fuzzy logic, as my own area of research is rather in logic-based fuzzy mathematics than formal fuzzy logic itself, so I can afford avoiding my own results completely; but I think there will be no danger for you, either, as I'm sure you're going to be reasonable enough when citing your own work. Best, LBehounek (talk) 12:20, 20 April 2008 (UTC)

Fine! It seems very reasonable. So we'll keep on doing some things. Best, --Carles Noguera (talk) 13:22, 20 April 2008 (UTC)