In France, we write d_1 // d_2 to indicate that the lines d_1 and d_2 are parallel.

I would like to have a "not parallel" symbol. What is the best way to do that ?

Advices alone are welcome.




$d_1 \parallel d_2$

  • Alternative to other answers, \usepackage{amssymb} for \nparallel.
    – kapple
    Commented Apr 3, 2021 at 3:00
  • 1
    @kapple No this is not my need. I want to strike // instead of || .
    – projetmbc
    Commented Apr 3, 2021 at 11:28

1 Answer 1


I would keep the slashes tighter; for the negation, the specular image of \smallsetminus seems good.




$a \parallel b \notparallel c$


enter image description here

  • Very good design and code. Thanks !
    – projetmbc
    Commented Oct 9, 2019 at 11:07
  • @projetmbc Try also with \mkern-6mu.
    – egreg
    Commented Oct 9, 2019 at 12:40

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