Talk:Nullity

message: This definition of nullity (for matrices) makes the rank-nullity theorem true by definition. Isn't there a definition for matrices that avoids this?
Yes there is.  I'm going to copy the definition of nullity out of my Linear Algebra textbook and see what I can do to expand on it/explain it.  Since it's a definition, hopefully this won't be construed as a copywrite violation.  Fieari 15:51, 16 May 2005 (UTC)
replies: text: Actually, I just checked and it seems to me that all the information about nullity can be found in Null space.  Perhaps nullity should simply redirect there?  I don't know enough about wikipedia to know how to go about making such a redirect, or who to ask that can make it happen. Fieari 16:02, 16 May 2005 (UTC)

text: Agree. I will make this a redirect now. Oleg Alexandrov 17:53, 16 May 2005 (UTC)
thread_title: The info in this article is contained in [[Null space]]

message: Now that it's a disambiguation page, can we delete the line pointing to division by zero, as it's pointed to in the next line (nullity (Transreal)).  — Arthur Rubin |  (talk) 15:24, 7 December 2006 (UTC)
replies: text: Done. --Tjohns   ✎ 15:32, 7 December 2006 (UTC)
thread_title:  Disambiguation 

message: Although I don't think it matters much, I'm not sure 'non-established' is an accurate description of transreal numbers -- doesn't the axiomatization and associated proofs more or less establish the system? I definitely agree that there should be some disclaimer on the link, but 'unadopted' or 'barely formalized' don't sound good. Is there a formally distinction between established and non-established math concepts that I'm not aware of? I'm mostly just curious and don't plan to change it. Eliot 17:45, 7 December 2006 (UTC)
replies: text: What other synonyms are there for "neologism" in mathematics?  That's what I was looking for.  — Arthur Rubin |  (talk) 17:48, 7 December 2006 (UTC)
replies: text: Amen to Arthur Rubin. Chutzpan 02:41, 27 March 2007 (UTC)
thread_title:  Established? 

message: I'm uncomfortable with having Richard Anderson's "nullity" under the heading "in mathematics". Presented as a mathematical concept, his transreal numbers are unsupported original research. There are no reliable sources for the math, but there are reliable sources for the media reaction to James Anderson, so I think the disambiguation should point to his article.
The typical misinformed math student who shows up here might not be able to look at "null space" and "transreal numbers" and figure out which one involves dividing 0 by 0, so I think clarification is necessary.
I don't hold a neutral POV here, so I won't go right ahead and make the change, but how about this for the disambiguation?
Nullity may refer to:
* Nullity (conflict), a legal declaration that no marriage had ever come into being
* The nullity of a mathematical operator, which is the dimension of its null space
* Nullity, a non-established mathematical concept that James Anderson (computer scientist) claims to enable division by zero
rspeer / ɹəədsɹ  18:20, 13 December 2006 (UTC)
replies: text: That looks fine to me. I'm going to go ahead and add it. --SonicChao talk 16:03, 16 December 2006 (UTC)
replies: text: Already been done by someone else. --SonicChao talk 16:05, 16 December 2006 (UTC)
replies: text: I don't see that in the history. Anyway, I've put in this version (but also included the word "controversial", which was added to the previous version of the page), because transreal numbers is now just a redirect to NaN. And the disambiguation of "Nullity" shouldn't point to "NaN", because that satisfies no one: those who want accuracy would object that NaN is an established concept and Nullity isn't, and James Anderson would object adamantly that Nullity is not NaN. rspeer / ɹəədsɹ  22:57, 16 December 2006 (UTC)
replies: text: Well, I have no objection to the change, but if you look closely at the version you replaced, "transreal numbers" linked to a section of Dr. Anderson's article. — Arthur Rubin |  (talk) 20:36, 17 December 2006 (UTC)

text: They can't be "supported" because there is nothing to "support" them, they are definitions (albeit useless ones, at least in my view), not hypotheses and definitions cannot be "supported". Also, "controversial" is too light a word -- NO serious mathematician takes "nullity" (as in this proposed "number" not as in the real mathematical meaning of nullity) seriously, so how much controversy is there anyway? mike4ty4 08:30, 17 May 2007 (UTC)
thread_title:  Not "in mathematics"