I am a mathematics professor and not a professional editor. But a mathematics manuscript has come to me for editing.

I see clearly that the phrase "C semigroup" needs an hyphen and I have inserted it. (Here C is some adjective denoting a special kind of semigroup).

But I don't know how to hyphenate "C contraction semigroup". Here the noun contraction seem to be working as an adjective.

I would be grateful to any sound suggestion.

closed as primarily opinion-based by curiousdannii, Mitch, NVZ, user66974, BladorthinTheGrey Dec 7 '16 at 16:50

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  • 2
    The journal should have a style guide you can refer to. If it doesn't then do whichever you prefer, there are no objective punctuation rules. – curiousdannii Dec 7 '16 at 8:22
  • If C-contraction is a type of semigroup, then no hyphen would seem to be necessary, though C-contraction-semigroup would be clearer as a modifier. As curiousdannii notes, however, this is a matter of style. Your style guide might stipulate that certain kinds of dashes be used in place of hyphens in one or the other position, for example. – choster Dec 7 '16 at 15:08

You're asking about a term of art in mathematics, and the conventions for typesetting these kind of things do not rely on the rules of English grammar or the style guidelines of non-technical punctuation. As far as I can tell, many journals use the rules listed below. Your example falls under rule number 5. If you've been asked to edit the manuscript for a journal or other organization, it's likely that the organization has a style guide that lays out the typographic rules the organization uses. Consult the appropriate stylist at that organization.

  1. Types of semigroups named without abbreviations generally do not use hyphens: symmetric semigroup. This is true, even when the name is a compound in which one might expect a hyphen: finitely presented semigroup.
  2. The exceptions to rule 1 are two: semigroups named for two mathematicians (Baer-Levi semigroup) and semigroups named with prefixes ordinarily hyphenated in non-mathematical contexts: quasi-commutative semigroup, intra-regular semigroup).
  3. Types of semigroups named with a single abbreviation use a hyphen: C-semigroup, N-semigroup.
  4. Types of semigroups named with an abbreviation followed by a word use a hyphen between the abbreviation and the word if the abbreviation applies to the word: R-commutative semigroup. In a commutative semigroup, you can switch adjacent semigroup elements in equations; R-commutative semigroups have a more complicated criterion for the switch, so the R applies to the type commutativity, and not the semigroup directly.
  5. Types of semigroups named with an abbreviation followed by a word do not use a hyphen if the abbreviation and the word apply separately and directly to the semigroup: C contraction semigroup. Here the C applies to the continuity property of the semigroup, and the contraction applies to the boundedness property of the semigroup.
  • Thanks for an excellent detailed answer. This clears many of my potential doubts. – P Vanchinathan Dec 7 '16 at 12:03

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