User talk:MathMartin/Archive3

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Contents 1 Group with operators 2 Decision problem 3 Norman Shapiro 4 De Boor Algorithm 5 Dynamical Systems 6 Nationalities 7 Angle brackets in TeX (\langle and \rangle)

[edit] Group with operators

If you've moved the subdefinition of 'Omega-group' from Zassenhaus lemma to its own page, we need to do something to make the later mention of 'Omega-subgroups' consistent with this move. Do you know what Bourbaki does in this case? Are they 'subgroups with operators'? That sounds a bit vague. mat_x 22:33, 4 March 2006 (UTC)

Yes you are correct the move was not really clean, I should have defined Omega-subgroup in the group with operators article. I will try to clean this up tomorrow. Bourbaki calls the subgroups, which respect the action of the operators, stable subgroups. From which source did you get the name Omega-group and Omega-subgroup ?MathMartin 22:52, 4 March 2006 (UTC)

I cleaned up the article group with operators and expanded the content a bit. I used the Bourbaki terminology but added alternative names where possible. At the moment I think the Bourbaki terminolgy is superior, especially considering the more abstract articles like stable sets under composition law and action on sets which still need to be written. But I admit I have not found a clear consensus on the terminolgy in the literature I consulted. MathMartin 13:17, 5 March 2006 (UTC)

I'm happy with the change in terminology. A graduate-level algebra professor of mine used the 'Omega...' terminology. I think he made it up so we wouldn't automatically go looking in books under 'groups with operators' for homework solutions. He also called nilpotent groups 'groups with property (N)' for a few months, until we knew better. mat_x 17:13, 5 March 2006 (UTC)

[edit] Decision problem

Hello, MathMartin.

I have encountered a problem while reading an article about decision problems. According to a definition you have given it is determining whether there exists a decision procedure or algorithm for a class S of questions requiring.... Later on it is written: For example, the decision problem for the class of questions "Does x divide y without remainder?" is decidable. Well, as I understand decidability is a property of decision problems. As in an example we have a problem: "Does x divide y without remainder?" and its meaning is exactly "if x divide y", not "if exist a procedure". The latter is a property of the decision problem, which can be undecidable, trivial, polynomial or something else.

I would suggest something like: "decision problem is a problem which admits only two possible answers yes or no", without formalizing the definition of the problem, which is intuitively known and difficult to formalize. Do you agree? kuszi 00:07, 20 March 2006 (UTC)

As far as I remember the part of the article, you are talking about, was not written by me. I am not quite sure I completely understand what you are talking about. Your formulation decision problem is a problem which admits only two possible answers yes or no is not enough for an intuitive explanation. The difficult part you are omitting is the definition of the formal system in which the decision problem has to be answered. Or to put it otherwise, it makes no sense to talk about a single instance of a decision problem, one has to deal with a set of problems which are related in some sense.

I agree that the introduction to the article is probably not accessible to non-mathematicians. Currently I do not have time to work on the article, so I would advise you to post your suggestions on the corresponding talk page Talk:Decision problem. MathMartin 15:58, 25 March 2006 (UTC)

[edit] Norman Shapiro

Hi there. I've added the "{{prod}}" template to the article Norman Shapiro, suggesting that it be deleted according to the proposed deletion process. All contributions are appreciated, but I don't believe it satisfies Wikipedia's criteria for inclusion, and I've explained why in the article (see also Wikipedia:What Wikipedia is not and Wikipedia:Importance). Please either work to improve the article if the topic is worthy of inclusion in Wikipedia, or, if you disagree, discuss the issues raised at Talk:Norman Shapiro. If you remove the {{prod}} template, the article will not be deleted, but note that it may still be sent to Wikipedia:Articles for deletion, where it may be deleted if consensus to delete is reached. Thanks. 66.167.136.142 09:10, 30 April 2006 (UTC).

Thanks for giving me a notice. I tried to beef up the article a bit, but I failed to find enough relevant material using google. So as far as I am concerned you are correct, he is probably not noteworthy enough to be included in wikipedia. MathMartin 12:02, 30 April 2006 (UTC)

Thanks. 66.167.137.203, f.k.a. 66.167.136.142 (talk · contribs) 20:21, 30 April 2006 (UTC).

[edit] De Boor Algorithm

Hello Martin, I am new to Wiki and had some problems to find out how to report a problem. I hope I am doing it right. Well here is the problem:

In the article DeBoor algorithm: (http://en.wikipedia.org/wiki/De_Boor_algorithm) the paragraph "Introduction" is misleading and contradicts the other paragraphs. It claims that the spline s(x) passes through the control points di. This is not true, the spline does NOT pass through the DeBoor control points. Further it should be mentioned, that the DeBoor algorithm takes control points and a value for the parameter and gives a spline point back. But the algorithm does not give any help in getting the control points from known curve points.

Daniel 62.2.237.193 07:02, 11 May 2006 (UTC)

I only did some minor editing on the article in question and cannot help you with the problem.

The correct place to report a problem like this is on the corresponding talk page Talk:De_Boor_algorithm. If you think there is a serious problem and you want to get the attention of more math people you might consider posting your problem at Wikipedia_talk:WikiProject_Mathematics. In any case you will certainly get more attention if you create a user account first.MathMartin 11:30, 12 May 2006 (UTC)

[edit] Dynamical Systems

Hello Martin, I'm the one who made the changes you have just reverted a while ago. You said What exactly did you correct ? Your edits made the equations wrong in my browser ! Perhaps there are some issues with the rendering of φ (In LateX there is phi and varphi)). Well, I corrected the style of the equations. I don't know what kind of browser do you have, but I checked the page after the minor changes I did, and it looked much better than your version. I use internet explorer and mozilla firefox. I have made two screenshots: after and before. Look at them, and the tell me what you don't like!

carlicus

Hi carlicus, welcome to wikipedia. You should sign your posts with ~~~~ which wikipedia automatically converts into your username and the current time and date.

Here is a screenshot of the version I reverted to on my browser (Linux + Mozilla):

Image:Dynamical System discussing rendering issues.jpg.

I think you can see now what the problem is. I will replace the lower case phi, which can be rendered ambiguously, with an upper case one. Have a look at the new version and tell me how it looks on your system. MathMartin 11:05, 6 October 2006 (UTC)

Oh, and to make matter even more confusing you can choose your own rendering style in the toolbar at the right top under my preferences->Math. MathMartin 11:23, 6 October 2006 (UTC)

[edit] Nationalities

Hi MathMartin, and welcome back. :) I have just a remark about nationalities. One should write "German" with big G, so not "german". Same for any other nationalities or languages. It is a small thing, but I thought I would let you know. You can reply here if you have comments. Thanks. Oleg Alexandrov (talk) 20:32, 15 October 2006 (UTC)

Thanks! I never seem to be able to remember the uppercase/lowercase spelling rules in english. I will try to remember, but do not count on it :) MathMartin 11:31, 16 October 2006 (UTC)

When giving the nationality of a scientist, what do we do about people who've lived in the United States for many years? For example, Andrew Yao is listed as a Chinese computer scientist although he's been in the US for a very long time, while some others born overseas as listed as Americans. Vegasprof 11:32, 21 November 2006 (UTC)

[edit] Angle brackets in TeX (\langle and \rangle)

In this edit, you wrote:

Please note that there's no need to use "<" and ">" in place of left and right angle brackets in TeX. You can just write:

Even the stripped-down version of TeX that is used on Wikipedia is sophisticated. Michael Hardy 19:39, 16 November 2006 (UTC)

Ok. Thanks. MathMartin 17:23, 23 November 2006 (UTC)

^{Superscript text}