# How do you do a $\Rightarrow$ with a slash through it in LaTeX (for “does not imply”)

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

Thanks.

• (This is not a support forum for LaTeX) – Mariano Suárez-Álvarez Apr 18 '12 at 1:58
• Oh, sorry -- I thought saw lots of LaTeX questions. But I found the answer -- \not\Rightarrow $\not\Rightarrow$ – David Lewis Apr 18 '12 at 2:48
• @DavidLewis" That, unfortunately, gives bad spacing; but lucky for you there is a pre-built command. – Arturo Magidin Apr 18 '12 at 2:52
• Please ask this at tex.stackexchange.com – Mariano Suárez-Álvarez Apr 18 '12 at 4:56
• 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. – Aryabhata Apr 18 '12 at 18:58
• 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. – Andrew Stacey Apr 21 '12 at 18:59

\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).

• How do you negate \implies? \not\implies gives poor alignment. Tx. – David Lewis Apr 18 '12 at 4:34
• The main difference between \implies and – Arturo Magidin Apr 18 '12 at 17:02
• Arturo is building the suspense... – Asaf Karagila Apr 18 '12 at 17:24
• Indeed! ${}{}{}{}$ – Mariano Suárez-Álvarez Apr 18 '12 at 17:29
• @DavidLewis You could use \kern; though it won't be perfect "\kern.6em\not\kern -.6em \implies" gives $\kern.6em\not\kern -.6em \implies$. – David Mitra Apr 18 '12 at 18:04
• @DavidMitra Perfect substitute for \nimplies – john Nov 10 '18 at 13:39