Talk:Level set

revision

Hello fellow editors,

I have revised the article, since it lacked references and contained too much technical information that belongs elsewhere. Please comment.

Sasha (talk) 19:37, 28 August 2011 (UTC)

Then I would like to know wehere the technical information belongs to? I really liked the section [[1]]

141.5.26.83 (talk) 15:56, 8 November 2011 (UTC)

It is possible that I erased too much, the picture is nice. But I do think the article should remain reasonably short. Sasha (talk) 20:07, 8 November 2011 (UTC)

I think you erased WAY too much, as the article borders on useless now to anyone who doesn't already know exactly what a level set is. As asked, if all that information doesn't belong here, then where does it belong? I definitely support a return to the version linked by the IP-user above. --Arvedui (talk) 21:03, 31 May 2012 (UTC)

I do not agree with your assessment of the content removed as "irrelevant". As for lacking sources, that should be very easy to correct. The terms "isotherm", "isobar", and so on, are in standard use. The proof of the gradient property can be found in any textbook on vector calculus. I have restored most of the deleted content. Sławomir Biały (talk) 17:00, 5 December 2013 (UTC)

Graphic

How about a graphic representation? It's key to economic theory.

I will do it myself if I think of it again after finals. 128.193.8.98 (talk) 21:35, 28 February 2012 (UTC)

The July 2011 version was superior

The current article contains no didactic content whereas the July 2011 one did, plus it had an awesome picture. A sign of how bad the current page is, is that I direct my students to the July 2011 page. http://en.wikipedia.org/w/index.php?title=Level_set&oldid=441776585. I guess it finally annoyed me enough to tell you about it. I don't want to step on anyone's toes so I'm not going to make changes. But seriously, change it back, or make an effort to improve the content of this page. 139.80.48.109 (talk) 03:37, 15 February 2013 (UTC)

Other definition?

In Johannes Jahn's "Introduction to the Theory of Nonlinear Optimization" it's

• (X, norm) a real normed space; S a nonempty subset of X; f: S \to |R a functional
• Epigraph E(f) = { (x, a) \in S \times |R | f(x) <= a }
• level set for a \in |R: S_a = { x \in S | f(x) <= a }

Looks like Jahn's level set is what's called "sublevel set" in this article. So maybe it should be mentioned that there are other definitions. -Quark8967 (talk) 22:08, 6 September 2014 (UTC)

Isn't this just the preimage?

Should this be linked with https://en.wikipedia.org/wiki/Image_(mathematics)#Inverse_image? 160.39.247.132 (talk) 14:45, 18 October 2018 (UTC)