I tried \cancel{\Rightarrow}, but perhaps I am installing the package improperly or something.


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    $\begingroup$ (This is not a support forum for LaTeX) $\endgroup$ Apr 18, 2012 at 1:58
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    $\begingroup$ Oh, sorry -- I thought saw lots of LaTeX questions. But I found the answer -- \not\Rightarrow $\not\Rightarrow$ $\endgroup$ Apr 18, 2012 at 2:48
  • $\begingroup$ @DavidLewis" That, unfortunately, gives bad spacing; but lucky for you there is a pre-built command. $\endgroup$ Apr 18, 2012 at 2:52
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    $\begingroup$ Please ask this at tex.stackexchange.com $\endgroup$ Apr 18, 2012 at 4:56
  • $\begingroup$ There is a difference in asking for (la)tex support which is available on Math.SE, vs plain (la)tex support. You will see lots of questions of the former type on meta.math but probably very few upvoted ones of the latter. $\endgroup$
    – Aryabhata
    Apr 18, 2012 at 18:58
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    $\begingroup$ The repost at TeX-SX has a little more context (see tex.stackexchange.com/q/52827/86) making it clear that the question is about packages with MathJaX. "How do I do X in MathJaX?" is off-topic on TeX-SX as it is not a question about TeX. Please only refer genuine TeX (including, but not limited to, LaTeX) questions to TeX-SX. $\endgroup$ Apr 21, 2012 at 18:59

3 Answers 3


\nRightarrow gives $\nRightarrow$

Added: For a thorough discussion of \implies vs. \Rightarrow, see this TeX.stackexchange question.

Unfortunately, it looks like \centernot is not supported in MathJax, nor is the solution using \ooalign


You can always write: $$\lnot(\varphi\implies\psi)$$


If you want to denote implication, it is usually best to use \implies from amsmath, which adjusts spacing (and dots).

  • $\begingroup$ How do you negate \implies? \not\implies gives poor alignment. Tx. $\endgroup$ Apr 18, 2012 at 4:34
  • $\begingroup$ The main difference between \implies and $\endgroup$ Apr 18, 2012 at 17:02
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    $\begingroup$ Arturo is building the suspense... $\endgroup$
    – Asaf Karagila Mod
    Apr 18, 2012 at 17:24
  • $\begingroup$ Indeed! ${}{}{}{}$ $\endgroup$ Apr 18, 2012 at 17:29
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    $\begingroup$ @DavidLewis You could use \kern; though it won't be perfect "\kern.6em\not\kern -.6em \implies" gives $ \kern.6em\not\kern -.6em \implies$. $\endgroup$ Apr 18, 2012 at 18:04
  • $\begingroup$ @DavidMitra Perfect substitute for \nimplies $\endgroup$
    – john
    Nov 10, 2018 at 13:39

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