1

I frequently encounter cases, such as the ones below, where you seemingly have two hyphenated compound adjectives modifying a noun. I know that in such cases that you should join the compound adjectives with an en dash.

However, in case (1) the author later wrote "...dual-hop MARNs...", using the initialism to denote the noun; thus, illustrating that "Multiple-access" is not a hyphenated compound adjective. Hence, my problem is what should be done in case (1). Should the noun be hyphenated right the way through to show that it is indeed one unit, as in "Dual-Hop Multiple-Access-Relay-Networks", or is their another way?

(1) Dual-Hop Multiple-Access Relay Networks

(2) Semi-definite Programming-based Approach

If you write (1) as "Dual-Hop(en dash)Multiple-Access Relay Networks, then I think this implies that "dual-hop relay networks" exist and that "multiple-access relay networks" exist independently of each other, which may not actually be the case.

Please help me out here because these things crop up so often in my work.

  • typo - "their" should be "there". – Robert Astle May 21 '14 at 6:15
  • Can you insert a footnote to explain that your terminology is intended to be purely descriptive, and is not intended to imply distinctions which may or may not exist? – Erik Kowal May 21 '14 at 6:41
  • These compound adjectives need no linking punctuation, they are understandable (and used conventionally all over) as such. By the way ndash is not used to join adjectives. Also consult applicable style guide if any. I would stick with (1) & (2) as they are fine. – Kris May 21 '14 at 6:54
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    The Chicago Manual of Style states: "The en dash can be used in place of a hyphen in a compound adjective when one of its elements consists of an open compound or when both elements consist of hyphenated compounds. This editorial nicety may go unnoticed by the majority of readers...". As I have already explained, they are not "clearly understandable" to me, and since I know nothing of the subject matter they are describing I may easily think that Relay Networks can be dual-hop and multiple-access, when in fact they may not be. – Robert Astle May 21 '14 at 7:14
  • I'm not an expert on relay networks, but I don't think dual-hop–multiple-access is supposed to be seen as one big compound adjective. They are just two separate compound adjectives and therefore require no en dash (or hyphen), just a simple space. In (2), you can indeed use a hyphen: semi(-)definite programming–based. – Janus Bahs Jacquet May 21 '14 at 7:31
3

You seem to be misunderstanding how compound adjectives and en dashes work.

As you yourself quoted, the Chicago Manual of Style says:

The en dash can be used in place of a hyphen in a compound adjective when one of its elements consists of an open compound or when both elements consist of hyphenated compounds.

This does not mean what you state in your first paragraph:

[…] cases, such as the ones below, where you seemingly have two hyphenated compound adjectives modifying a noun. I know that in such cases that you should join the compound adjectives with an en dash.

It is not the case that you should join two hyphenated compound adjectives modifying a noun with an en dash, or with anything else for that matter. Two separate adjectives (whether compound or hyphenated or not) should never be joined by anything—that’s why they’re separate.

(For our present purposes, I will simply refer to ‘adjectives’, though none of the examples you give actually contains any adjectives at all: they are all adjunct nouns. For hyphenation purposes, though, adjectives and adjunct nouns work the same.)

In your first example, you have such a scenario: relay networks is modified by two separate adjectives, both of which happen to be compound: dual-hop and multiple-access. (Or more precisely, as you’ve also pointed out, you have a noun phrase, multiple-access relay network, which is modified by a single compound adjective, dual-hop.) As such, no linking of the two adjectives is called for, any more than it would make sense to write “big–red relay networks” rather than just “big red relay networks” (if indeed networks had colours).

 

The only time you (can) use the en dash is when you have a compound adjective one or more of whose components are themselves compound phrases.

Your second example is such a case: the compounding here is between semidefinite programming (or semi-definite programming) on the left hand side, and based on the right hand side. Since semidefinite programming is an open compound in itself, and you are using it as one of the elements in a compound adjective, you have the choice of using an en dash to clarify the compounding:

  • Semidefinite programming-based (hyphen): Ambiguous; could refer to something semidefinite that is programming-based, or to something that is based on semidefinite programming.
  • Semidefinite programming–based (en dash): Unambiguous; the en dash tells you that the compound consists of more than just the words directly linked together by it, including also the previous words (as many as makes sense).

Examples where both elements of the compound adjective are themselves compound adjectives are harder to come up with. The only example Chicago gives is a quasi-public–quasi-judicial body, which as they note works better if you simply take the two compound adjectives as separate: a quasi-public, quasi-judicial body (similar to your first example).

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  • I think the terminology you use is incorrect. "Dual-Hop" is a hyphenated compound acting as an adjective. Likewise is "Multiple-Access". Therefore, I now have two adjectives, and hence a compound adjective. Both elements of the compound adjective can be joined by an en dash as stated in the CMOS. This is indeed the case with the elements "quasi-public" and "quasi-judicial", both of which are adjectives (hyphenated as the case may be) forming a compound adjective that can then be joined with an en dash. – Robert Astle May 21 '14 at 8:26
  • The case "a quasi-public, quasi-judicial body" occurs because the compound adjectives (hyphenated thought they may be) are acting as coordinate adjectives. Thus, implying that the "body" in question can be both a quasi-public one and a "quasi-judicial" one. – Robert Astle May 21 '14 at 8:31
  • I am unsure whether I can write "dual-hop, multiple-access relay networks", which would suggest that the relay networks are both dual-hop and multiple-access. From the above, as mentioned earlier, the author later wrote dual-hop MARNs implying that "multiple-access relay networks" was the noun phrase and that only such networks could be dual-hop. – Robert Astle May 21 '14 at 8:36
  • Whose to know the difference between "Dual-Hop Multiple-Access Relay Networks", where the two compound adjectives are NOT coordinate but act together as a single unit to modify the noun "relay networks" and "Dual-Hop Multiple-Access Relay Networks", where only "dual-hop" modifies the noun phrase "Multiple-Access Relay Networks"? – Robert Astle May 21 '14 at 8:44
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    The terminology I'm using is simplified, but not incorrect. However, saying, “Therefore, I now have two adjectives, and hence a compound adjective” is incorrect. Two adjectives do not a compound adjective make. A compound adjective is most prominently characterised by having only one head (and thus only one primary stress) and is syntactically a single adjective. I cannot conceive of how dual-hop–multiple-access can semantically be a single adjective. – Janus Bahs Jacquet May 21 '14 at 8:58

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