After reading several papers, I started to wonder which types of arrows are used for what purpose. There are (generally spoken) two kinds of arrows: The short ones like \Leftrightarrow and the long ones like \Longleftrightarrow.

I got the feeling that for definitions, the longer variants are used, while for logical expressions, the shorter ones are more common. Are there any regulations or conventions?

  • 3
    This is not a typographic, but a notation question, probably better suited for the math forum. However, if an arrow is to be modified by a letter or longer expression above or below it, the longer form is always used. Sep 28, 2020 at 3:16
  • If this is really a question in logic, whether to use an arrow at all and, if so, which one is a function of the syntax specified by the proof system you're using (or defining). So a double arrow is sometimes used for the conditional, but sometimes something else is used instead. The horseshoe is a common choice. Although LaTeX is better at typesetting logic than word processors (were?), logic has always seemed to get rather short shrift. Few of the packages supporting it are in the major distributions and little works properly out-of-the-box. There's a bit of a lacuna where logic should be.
    – cfr
    Dec 4, 2020 at 4:03
  • ^^ is not to disagree with @barbarabeeton. It is a notation question. Just, if you are really in the realm of symbolic logic, there's no answer independent of a choice of notation. (But there may be typographic reasons to use a longer or shorter version of a given arrow, if the system doesn't determine the choice.)
    – cfr
    Dec 4, 2020 at 4:10


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