Notation
The negation of a proposition p is notated in different ways in various contexts of discussion and fields of application. Among these variants are the following:
Notation  Vocalization 

¬p  not p 
−p  not p 
~p  not p 
Np  en p 
p prime, p complement 

p bar, bar p 

bang p not p 
In Set Theory \ is also used to indicate 'not member of': U \ A is the set of all members of U that are not members of A.
No matter how it is notated or symbolized, the negation ¬p / −p can be read as "it is not the case that p", "not that p", or usually more simply (though not grammatically) as "not p".
Read more about this topic: Negation