Abstract
I consider the issue of optimal targeting in information diffusion networks. The initial information possessor is to target a single node so as to diffuse the information to all other nodes most effectively. For the purpose, the concept of closeness centrality may be useful, but if the value from delayed information is discounted by a discount factor, the concept should be properly modified. With this respect, I propose a modified concept of closeness centrality which I will call δ-(closeness)-centrality. The δ-centrality of a node is defined by the sum of discounted values generated from information transmission starting from the node given discount factor δ. Some advantages of δ-centrality over the closeness centrality are discussed.
