Talk:Undefined (mathematics)

Proposed rewrite

As of 2 December 2024, this article is in an unfortunate state. There's a lack of rigor, focus, and concision. And much of the article is demonstrably wrong. That's a shame, because the topic is incredibly important to learners of mathematics. The mathematical concept of "undefined" causes much confusion for young people.

So, I've undertaken to tear the whole article down and rewrite it from first principles: simply, directly, and with a reasonable quantity of mathematical rigor. I've included a bunch of references and other background material, supporting the rewrite. Unlike the current article, this rewrite observes Wikipedia:Manual_of_Style, Wikipedia:Make_technical_articles_understandable, Wikipedia:Neutral_point_of_view, Wikipedia:No_original_research, Wikipedia:Citing_sources, and Wikipedia:Verifiability.

Critically, I think this rewrite will be a much more solid basis for the editors that come after me.

The current draft of my rewrite is online at User:Johnwbyrd/Undefined_(mathematics). Feedback and further edits are welcomed to this draft. If there are no strong objections, I'll wait a reasonable amount of time, and then rewrite the entry.

- John Byrd (talk) 21:46, 2 December 2024 (UTC)

Reorganisation

I've added section headings to previous comments on this page, indenting as necessary, to help us all discuss the substantive issues. yoyo (talk) 13:13, 10 July 2018 (UTC)

In computer science

Can someone provide a reference for the "Notation using ↓ and ↑" section? I needed to figure out where this notation is defined and I can't believe I'm the only one. Shawnmjones (talk) 01:00, 9 September 2014 (UTC)

Never mind, I found a source and added it.

Shawnmjones (talk) 01:26, 9 September 2014 (UTC)

The article's about the semantics of "undefined" (and hence "defined"), not about what syntax is read using these terms. So this section needs to explain what those terms mean in computability theory. yoyo (talk) 13:13, 10 July 2018 (UTC)

Current problems

Mathematical clarity

I'm afraid the whole article is missing mathematical clarity and precision. It's mostly an artistic representation of things. It should be either rewritten, or, at least, edited a lot. Vlad Patryshev (talk) 03:03, 24 September 2016 (UTC)

Vlad is correct. This entire article is terribly written. It needs to be entirely taken out behind the barn and shot. In its place, the article needs to be rewritten in a much more formal and concise manner. I'll do this if no one else will.

--John Byrd (talk) 20:36, 20 November 2024 (UTC)

Why would anyone term it "artistic"? Do please explain that, if you like.

With few exceptions, I found the article singularly clear:

1. The lead paragraph summarises three contexts as bullet points, which might give the impression that only three such contexts exist, whilst the article clearly discusses more than three. So I've added a few words to clarify that: "Such contexts include the following, among others".
2. The article purports to be about the use of the term "undefined" in mathematics. Yet the § Notation using ↓ and ↑ section is about its use in computer science – arguably a scientific field of study that applies mathematics, rather than is mathematics. (Or not!) On these grounds, it doesn't belong in this article, but rather in a disambiguation (DAB) page for the (unqualified) term "undefined". But if we were to agree that CS is maths, then we may not need the DAB page after all. See further discussion under the section heading "Focus" below. yoyo (talk) 13:13, 10 July 2018 (UTC)

Focus

In 2015, an editor tagged this page using the {{incoherent}} template, which states

This article may lack focus or may be about more than one topic. Please help improve this article, possibly by splitting the article and/or by introducing a disambiguation page, or discuss this issue on the talk page.

I believe the article is well-focussed and about one topic, so would favour removing that template. The only evidence I've seen that the article lacks focus is this: its name says that it's about the term "undefined" in mathematics, yet it also includes a brief section mentioning how it's the reading of certain notation in computer science (which may, or may not, be considered as a part of mathematics). Do we perhaps need a (very simple) disambiguation (DAB) page for the (unqualified) term "undefined"? That page would distinguish the fields that use such a term, e.g.

1. in mathematics
2. in computer science
3. in philosophical logic
4. …

Even if that's so, this page is not that (DAB) page. It already has much more information about specific mathematical uses than we like to see on a DAB page, whose purpose is to help readers navigate to articles relevant to their needs, and therefore usually restricts itself to a one-sentence description and a single wikilink. yoyo (talk) 13:13, 10 July 2018 (UTC)

Russian translation equivalent sense for words undefined and indeterminate

0/0 is indeterminate, russian word equivalent sense will be "неоднозначно".
10/0 is undefined, russian word equivalent sense will be "неопределено".
188.208.126.82 (talk) 13:17, 9 June 2023 (UTC)