Notation for "A does not imply B" I'm looking for a way to express A being true does not imply B. I know that A implies B can be written as $A \rightarrow B$, but what about A does not imply B? $A \not\rightarrow B$? 

Usually, we use double arrows for implications: $A\Rightarrow B$.  You can use a crossed out double arrow for does not imply: $A\nRightarrow B$.  In LaTeX, these are "\Rightarrow" and "\nRightarrow", respectively.
