This paper studies a problem in the online targeted marketing setting called the least cost influence problem (LCIP) that is known to be NP-hard. The goal is to find the minimum total amount of inducements (individuals to target and associated tailored incentives) required to influence a given population. We develop a branch-and-cut approach to solve this LCIP on arbitrary graphs. We build upon Günneç et al.'s novel totally unimodular (TU) formulation for the LCIP on trees. The key observation in applying this TU formulation to arbitrary graphs is to enforce an exponential set of inequalities that ensure the influence propagation network is acyclic. We also design several enhancements to the branch-and-cut procedure that improve its performance. We provide a large set of computational experiments on real-world graphs with up to 155 000 nodes and 327 000 edges that demonstrates the efficacy of the branch-and-cut approach. This branch-and-cut approach finds solutions that are on average 1.87% away from optimality based on a test-bed of 160 real-world graph instances. We also develop a heuristic that prioritizes nodes that receive low influence from their peers. This heuristic works particularly well on arbitrary graphs, providing solutions that are on average 1.99% away from optimality. Finally, we observe that partial incentives can result in significant cost savings, over 55% on average, compared to the setting where partial incentives are not allowed.
KEYWORDSexact method, influence maximization, integer programming, strong formulation
INTRODUCTIONOnline communication (through social networks, newspapers, blogs, shopping websites, etc.) has become one of the main resources for information sharing. A recent report (see [27]) shows that in the United States people consider online social networks to be one of the most effective ways for disseminating information, and two-thirds of the population use their online social networks as one of the channels for receiving information and news. Not surprisingly, people's decisions are affected by the information they receive through social media. While peer influence has been recognized as a role exerting an important impact in decision-making for a long time (see e.g., [1,2,9]), online social media provide a much easier and more convenient way to track the interaction of online customers based on their footprints. It opens an opportunity for researchers to understand social networks and manage their effects on purchasing decisions. The outcomes can be used as an essential part of creating successful online marketing strategies. As a result, there is an increasing interest in correctly identifying (targeting) customers that are most likely to help the spread of a product (or information) over a social network.Indeed, Chen [3] initiated a stream of work in this area focused on identifying the fewest number of nodes to target in order to influence an entire network. However, the mathematical models studied by Chen and many other researchers for such influence maximization pro...