I'm wondering in what direction we construct reductions to prove that a problem is NP-complete. Say the question is asking to prove that the vertex cover problem is NP-complete given that the independent set problem is NP-complete.
In this case, do we start with an instance of the vertex cover problem and show how we can transform this instance into an instance of the independent set problem? Or, do we start with an instance of the independent set problem and transform it into an instance of the vertex cover problem?
I understand the relationship between vertex cover and independent set, however, I am confused on the direction of reduction.