The closure of a graph $G$, denoted $cl(G)$ is defined to be the supergraph of $G$ obtained from $G$ by recursively joining pairs of nonadjecent vertices whose degree sum is atleast $n$ untill no such pair exists.[n=|V(G)|]
Here if we add edges to non agecent vertices with $d_G(u)+d(v)\ge n$, adding edge $uv$ means $d_{G+uv}(u)+d_{G+uv}(v)=d_G(u)+1+d_G(v)+1\ge n+2 > n$ still the degree sum is more than n. Can you please help me to understand the definition?