Formatting a citation to a MathOverflow answer

Question

What's a good way to format a citation to a MathOverflow post in a paper? Here is a first draft (with hyperlink, and assuming it's reference number 16, say), but maybe people can think of improvements:

[16] Pietro Majer, answer of April 8, 2014, 17:26pm HST to MathOverflow question 162724, Smooth convex extensibility of combination of two line segments.

(Related question: does the software know my time zone when it displays the time of day of an answer on screen?)

Answer 1

On the main site, the (nearly invisible) cite button found in the share menu gives an example citation and gives both bibtex and amsref misc entries that are easy to cut and paste.

Unfortunately, the mechanism to generate the bibtex entry has some bugs.

@MISC {22350,
TITLE = {What are some examples of colorful language in serious mathematics  papers?},
AUTHOR = {François G. Dorais (http://mathoverflow.net/users/2000/francois-g-dorais)},
HOWPUBLISHED = {MathOverflow},
NOTE = {URL:http://mathoverflow.net/q/22350 (version: 2010-04-23)},
EPRINT = {http://mathoverflow.net/q/22350},
URL = {http://mathoverflow.net/q/22350}
}

To get a proper entry from this:

• First decode any HTML encoded characters. For example, &#231 above should be replaced by ç, {\c c}, or equivalent. If you use special characters like ç, make sure to use the LaTeX package inputenc with the appropriate encoding option (e.g. utf8). Also use bibtex8 since the original bibtex only supports the 7-bit ASCII character set.

• Since bibtex tries to parse the author field and break it into parts (first, last, suffix, etc.), it is best to remove the parenthetical link to the user profile since that will often break the parsing mechanism. (An alternative is to only use the link to the user profile and delete the name, but that might lead to sorting issues.)

• Since this post is an answer rather than a question, consider editing the title to make this clearer. You may also consider changing the URL to http://mathoverflow.net/a/22350.

• Bibtex traditionally only supports YEAR and MONTH of publication, which is unfortunately too coarse for MO posts. Fortunately, many styles do recognize the DATE field; consider adding it. If the post has a nontrivial revision history, you may want to put a date other than the first posting.

• If the bibtex style you use does recognize the EPRINT or URL fields, the visibly redundant entries containing the post URL could result in it being printed two or three times. Consequently, you may have to remove some of these entries to fit your preferred bibtex style.

• If you use the hyperref package, you could also wrap the URL in a \url command in the NOTE field so that it becomes clickable. Do not do this for the URL field since styles that use this field will normally do the wrapping for you. A few styles support the URLDATE field which, combined with URL, is perhaps a better alternative than the given NOTE field.

• The use of the EPRINT field is extremely style dependent. Some styles will do something reasonable with the field given above but many more will not. Maybe there is some style out there that understands EPRINT but not URL. Unless you use that style, it's probably better to remove the EPRINT field.

After all these recommendations, you get something that should work reasonably well with most styles:

@MISC {22350,
TITLE = {What are some examples of colorful language in serious mathematics  papers? (answer)},
AUTHOR = {François G. Dorais},
HOWPUBLISHED = {MathOverflow},
DATE = {2010-04-23},
NOTE = {URL:\url{http://mathoverflow.net/a/22350} (visited on 2014-04-22)},
URL = {http://mathoverflow.net/a/22350},
URLDATE = {2014-04-22},
}

I guess the best advice is to get to know the bibtex style you use and figure out the best way to format a MO bibtex entry for that style. Unfortunately, publishers will often force authors to use peculiar styles. If that's the case, ask the editor to explain how to properly format a MO bibtex entry for that style.

Answer 2

Users of the biblatex package can use an @online entry type. From the biblatex documentation:

online: An online resource. author, editor, and year are omissible in terms of §2.3.2. This entry type is intended for sources such as web sites which are intrinsically online resources. Note that all entry types support the url field. For example, when adding an article from an online journal, it may be preferable to use the @article type and its url field.

Required fields: author/editor, title, year/date, url

Optional fields: subtitle, titleaddon, language, version, note, organization, date, month, year, addendum, pubstate, urldate

Here is a reasonable example:

@online{MO22350,
  title = {What are some examples of colorful language in serious mathematics  papers?},
  titleaddon = {(answer)},
  author = {François G. Dorais},
  date = {2010-04-23},
  version = {1},
  organization = {MathOverflow},
  url = {http://mathoverflow.net/a/22350},
  urldate = {2014-04-19},
  nameaddon = {http://mathoverflow.net/users/2000},
}

Since MathOverflow user names and titles may contain special characters, use the package inputenc with option utf8 before using the biblatex package in the document preamble, or manually replace special characters by appropriate encoding (e.g. ç by {\c c}). (Also consider using Biber instead of BibTeX as a backend.)

The nameaddon field is not used by standard bibliographic styles but that is what it is used for in styles that do use it; a note field could be used with similar effect with greater compatibility.

---

Sample output for the entry above:

With biblatex options backend=biber,style=authoryear.

Answer 3

I am using a nonstandard citation format, primarily for simplicity. An example is:

MathOverflow Questions (Number refers to URL, so 37679 expands to "http:// mathoverflow.net/questions/37679") [Note: the current display scripts replace the URL with a visible title and hidden link: I've added a space to break this feature. My actual example would not have the space.]

88323 Analogues of Jacobsthal's Function.

56099 Lower bound of the number of relatively primes (each other) in an interval.

68351 Least Prime Factor in a sequence of 2n consecutive integers.

Since I am not interested in making changes when URLs change or databases change, I prefer to provide a simple recipe for translation to avoid as few broken links as possible. I also let the user grab the date from the paper or its metadata, so they can provide their context.

If I were to improve upon this, I might add something like "at this writing 2014.03", as well as provide links to specific versions of the post as suggested by quid. I would refrain from referring to something more specific than the post and its answers; if I had to, I would craft a similar recipe, such as:(Number;version refers to URL, so 37679;38690/1 refers to https://mathoverflow.net/revisions/37679/38690/1). The rationale for this is to give a simple recipe that works at the time the document was publicized, and let the future researcher modify the recipe as needed to resolve the references. If I have to change anything, I only need to change the recipe, not all of its occurrences, unless the question numbering changes.

Gerhard "Prefers Simplicity, Replicability Over Ultra-convenience" Paseman, 2014.04.17