[Tex/LaTex] When to use \dots, \ldots, \cdots, and blanks?


I am writing math. questions like these:

  • Complete the missing numbers: 3,4,…,…,7
  • 5+…=7
  • The rectangle contains four … angles (choices: acute, obtuse or right)

In each case of the mentioned ones, which is the suitable to use? (dots – ldots – cdots – a blank)

Best Answer

AMS offers several dot (ellipsis) styles, use the one matching your intent:

  • \dotsc: For use between commas, e.g a, b, \dotsc, z
  • \dotsb: To elide binary operators, like a_n z^n + a_{n - 1} z^{n - 1} + \dotsb + a_0
  • \dotsm: Ditto, multiplications, as in n! = n \cdot (n - 1) \dotsm 1

There is also a set for use in arrays (matrices).

In general, I've found that the extra work to select the precise alternative instead of hoping LaTeX will Always Do The Right Thing is minimal, and pays off in better results (as said LaTeX selection is based on very limited information).