When both "Mathjax" and "Display emoticons as images" filter are activated, some Mathjax expressions do break, because they are processed by the "Display emoticons as images" filter later on. The one mentioned in this issue's title is an example.

Steps to replicate:

• Enable "Mathjax" and "Display emoticons as images" filter to your page, in "Manage filters" admin/filters.php having them apply to content, place the "Display emoticons as images" filter under the "Mathjax" filter.
• Go to a course.
• Insert a label, fill it with an

  y(n)

  
  expression

  \( y(n) \)

  .

• Insert a label, fill it with an

  y(t)

  
  expression

  \( y(t) \)

  .

• Note that the

  y(n)

  
  expression is breaking since the

  (n)

  is displayed as a "thumb down" emoticon. The y(t) though, converts correctly.