LaTeX Symbol for a not related to b Typically you have a relation R like this --> aRb. However, I am trying to find the symbol "opposite" of R, to say a is not related to b. It looks like R, but with a diagonal line through it. What is the LaTeX command for this symbol? 

Something like this? $a \not\mathrel{R} b$
If so, type: \$a \not \mathrel{R} b\$.
You didn't mention this, but if you also prefer using the notation $a \sim b$, where $\sim$ is the relation, then $a \nsim b$ is typed as \$a \nsim b\$.
