In mathematics and physics (and other fields of science), it is quite common to use symbols in lieu of names. For instance an object can have a symmetry G, i.e. the name of the symmetry is G.

I am wondering what are the rules for hyphenation when using the adjective version. Does one say that an object is G-symmetric or G symmetric?

In scientific papers, I've seen versions with and without hyphens, sometimes in the same document.

I would expect that the rule should be as for any compound adjective, i.e. hyphenated if attributive and not if predicative. However, to my non-native eyes, saying "this object is G symmetric" doesn't look correct. Is there any rule or at least partial consensus on this?

  • The "rule" about before but not after nouns has MANY exceptions according to various style guides. One example is CMOS 7.85. It has an answer to your question and that answer would apply when you use that expression as a noun too ... BUT, "take a packed lunch" (or a bottle of hard liquor) before trying to research your answer. :) It is the most horrendously designed and presented document I have ever had the misfortune of wasting hours of my life attempting to comprehend. :( Feb 8, 2018 at 3:12
  • 3
    PS I would hyphenate G-compound in all situations with no fear anyone may consider my choice was wrong. Feb 8, 2018 at 3:17

1 Answer 1


Based on my personal experience as a professional scientist, I feel that these things are more often hyphenated than not. I must admit that I do not know whether there is a strict rule on this (though I feel there isn't and it's more a style-related issue). However, you can always look these issues up in the appropriate style guide. Since I'm a chemist, I can refer you to the American Chemical Society (ACS) Style Guide, 3rd edition (2006), which states on page 142:

Hyphenate unit modifiers made up of a single letter or number and a noun or adjective.

Or, in other words, it's G-symmetric.

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