What do these symbols where the arrow point to mean? Does it mean not less then? If that's the case, why do we write it that way and not > if they are the same?
[Math] What do more than or less than sign with a line through them mean
discrete mathematicsnotation
Best Answer
$0\not<1$ means ‘$0$ is not less than $1$’, just as $a\ne b$ means ‘$a$ is not equal to $b$’. This is not the same as $0>1$; it is the same as $0\ge 1$, but in this case I suspect that $p$ is $0<1$, and the writer preferred to write the negated relation in a way that made the connection with $\sim p$ (‘not $p$’) obvious