en-dash

Type-setting: The use of hyphens and en-dashes

From "The TeX-Book" (Knuth) and "The Joy of TeX" (Spivak):

Hyphens are used for compound words like "daughter-in-law" and "X-rated". En-dashes are used for number ranges like "pages 13--14", and also in contexts like "exercise 1.2.6--52". (The TeX-Book, p.4)

En-dashes are used for number ranges, like "pages 13--34", and also in contexts like "Fig. A--12". (Joy of TeX, p.8).

The AMS-proposal

It seems that it was common practive to use a hyphen for dealing with pairs of names (like Auslander-Reiten), but then the problem arose: what to do, when one of the names involved uses already a hyphen. The publishers of the AMS suggested in this special situation to use an en-dash for the combination of names, and to use this rule then throughout the paper.

TeX - stack exchange

For a long discussions about the problem see tex.stackexchange.com. Here, the use of an en-dash for pairs of names is rated as a suggestion of some typographers with the addition: "(i.e. they consider it a possible way to do things, not a compulsory one)"

Clear rules:

you should use a longer sign when the link between the two elements of the phrase is weaker, and a shorter one when they are very much related.
Important is the uniformity all along a document.

Conclusion

The compound rule means to write Auslander-Reiten--quiver, but definitely not Auslander--Reiten-quiver.

The problem

This is the problem: There are three levels of compounds:

Double names: e.g. Swinnerton-Dyer.
Names of different authors: e.g. Aulander-Reiten.
The combination of names with an object: e.g. Serre-formal

but there are only two typographical means: the hyphen (-) and the en-dash (--).

Two examples from Advances in Mathematics

hyphen for "Yang-Baxter" (good)

en-dash for "Auslander-Gorenstein", hyphen for "Serre-formal"				Comment: This is really strange. How would they typeset "XXX-formal", if the concept of formality would have been introduced not by Serre, but by Auslander-Gorenstein: as "Auslander--Reiten-formal"?

There are not many journals where the TeX-files of the articles are available. One is JIS. There is the paper 20.6.7 entitled "Explicit Asymptotics for Signed Binomial Sums and Applications to the Carnevale-Voll Conjecture", see JIS-20.6.7 Here is the TeX-Code for the title:

  {\LARGE\bf Explicit Asymptotics for Signed Binomial\\
  \vskip .01in
  Sums and Applications to the Carnevale-Voll
  \vskip .10in
  Conjecture}

(Similarly, see "Thue-Morse Sequence" in Article 20.8.2)

Outside of the math community

See for example fonts.com (Keyword: Hyphens, En-dashes and Em-dashes, by Ilene Strizve):

A hyphen is the shortest in length of the three. It is used ... to connect parts of compound words such as go-between, ill-fated...

The en-dash, which is shorter than an em-dash and longer than a hyphen, is used to indicate a range of values, such as a span of time or numerical quantities (similar to using the words "to" and "from"). Examples: 5:30 -- 6:00 pm, Monday--Friday, 1984--2002.

Or see: grammerly blog (Keyword: En Dash, by Catherine Traffis): Using an En Dash with Complex Compound Adjectives:

An en dash should be used for clarity when one of the elements in a compound adjective is an open compound (made up of two words with a space between them) or when both elements contain hyphenated terms. Examples: Ming Dynasty-style furniture, World War I-era