This question has always haunted me, so I decided to settle it for good. Suppose I am saying "We provide space-and time-efficient algorithm for approximating [the number of cats in apartment building]". Here, is my us of hyphen in "space-and time-efficient" correct?

EDIT: So, one way of saying this is "Our algorithm is space efficient, and also time efficient". Now, I would like to shorten this by something like "space-and time-efficient". My question is, do I need a hyphen after "and"? Or, how to correctly hyphenate in this particular case? Although the links in the comments do deal with similar problems, their case is just that -- similar, but not identical to mine.

  • It’s never correct to use an em dash when a hyphen is required. Have you researched the difference between the two? Commented Jun 27, 2019 at 13:50
  • You haven't used em dashes (—); you've used hyphens (-). Are you asking how to hyphenate compound adjectives or are you asking about how to present parenthetical information? Any on-topic answer given will depend entirely on the topic of your question—which isn't clear. Commented Jun 29, 2019 at 11:40
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    While the nominated duplicate may not at first glance seem relevant, please read the answer. Your phrase is almost correct, but space- needs a space after it (it shouldn't be hyphenated to and).
    – Andrew Leach
    Commented Jun 29, 2019 at 11:52
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    See also Can a hyphen be used without anything on the right side
    – Andrew Leach
    Commented Jun 29, 2019 at 12:16
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    The updated version of your sentence requires neither hyphens nor dashes. Our algorithm is (both) space and time efficient. If you aren't using hyphenation with the single words, then using a conjunction with them doesn't change that. However, if you said I have a space-efficient heater and I have a time-efficient heater (each being hyphenated), then the combination would be I have a space- and time-efficient heater. Commented Jun 29, 2019 at 16:28


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