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This is a soft question.

Context: In mathematics, one often writes in boldface to signify certain mathematical objects. For example, we might write $c$ to signify a real number, and yet write $\mathbf{c}$ to signify a column vector of real numbers.

The problem is that it is hard to write $\mathbf{c}$ on paper or a chalkboard/whiteboard; writing $\mathbf{c}$ on paper just looks like writing $c$.

Of course, we never run into this problem on math.stackexchange because we write in latex.

Question: Is there some widely held convention in the mathematics community that allows one to signify bold letters when writing on paper (or chalkboard/whiteboard)? Underlining? Underlining twice, or some such practice?

user1770201
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  • While writing on a board, you choose your own notation, so there is never any need to use bold (though the blackboard font is meant to replicate it). – Tobias Kildetoft Sep 16 '16 at 19:08
  • The slightly cheeky answer is to use bigger chalk. I had a prof who always wrote with sidewalk chalk on the chalkboard... certainly looked much bolder than traditional "small" chalk. – TravisJ Sep 16 '16 at 19:09
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    When I write vectors by hand (and only when I need to distinguish them from scalars) I fall back to the old-school $\vec c$ notation. –  Sep 16 '16 at 19:23

1 Answers1

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The standard marking, in the sense of standard proof correction marks, for boldface is to underline with a wavy line. (A straight underline is for italic, and underlining twice is for small caps.)

While this is standard in a way I doubt this is all that widely known nowadays (I'll confess I had to look it up to recall which type of line it was).

There is also the font-family called blackboard bold that you surely know $\mathbb{A,B,C,N,Z,Q,R}$ hinting at another way to write bold on the blackboard, namely draw some lines twice.

For practical purposes, I suggest to do whatever works well for you. Likely underlining with a straight line is preferable to the 'standard' wavy line in this context, as likely you will not have the need to also signal italic.

quid
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