I have an example for a reduction of 3CNF to Clique, there is one thing I don't get about it, hopefully you could clarify it. The reduction works like this:

> 
> Construct a graph G = (V, E) as follows:
> 
> 
> Vertices: Each literal corresponds to a vertex.
> 
> 
> Edges: All vertices are connected with an edge except the vertices of
>  the same clause and vertices with negated literals.
> 
> 
> 

Why is it important that that negated literals will not be connected? How would that effect the reduction?