__ABSTRACT:__
As both social network structure and strength of influence between individuals evolve constantly, it requires to track the influential nodes under a dynamic setting. To address this problem, we explore the Influential Node Tracking (INT) problem as an extension to the traditional Influence Maximization problem (IM) under dynamic social networks. While Influence Maximization problem aims at identifying a set of k nodes to maximize the joint influence under one static network, INT problem focuses on tracking a set of influential nodes that keeps maximizing the influence as the network evolves. Utilizing the smoothness of the evolution of the network structure, we propose an efficient algorithm, Upper Bound Interchange Greedy (UBI) and a variant, UBI+. Instead of constructing the seed set from the ground, we start from the influential seed set we find previously and implement node replacement to improve the influence coverage. Furthermore, by using a fast update method by calculating the marginal gain of nodes, our algorithm can scale to dynamic social networks with millions of nodes. Empirical experiments on three real large-scale dynamic social networks show that our UBI and its variants, UBI+ achieves better performance in terms of both influence coverage and running time.

__EXISTING SYSTEM:__- Zhuang et al. study the influence maximization under dynamic networks where the changes can be only detected by periodically probing some nodes. Their goal then is to probe a subset of nodes in a social network so that the actual influence diffusion process in the network can be best uncovered with the probing nodes.
- Zhou et al. have achieved further acceleration by incorporating upper bound on the influence function.

__DISADVANTAGES OF EXISTING SYSTEM:__- Traditional algorithms for Influence Maximization become inefficient under this situation as they fail to consider the connection between social networks at different time and have to solve many Influence Maximization problems independently for social network at each time.
- All the previous methods aim to discover the influential nodes under one static network.

__PROPOSED SYSTEM:__- In this paper, we propose an efficient algorithm, Upper Bound Interchange Greedy (UBI), to tackle Influence Maximization problem under dynamic social network, which we term as Influential Node Tracking (INT) problem. That is to track a set of influential nodes which maximize the influence under the social network at any time.
- The main idea of our UBI algorithm is to leverage the similarity of social networks near in time and directly discover the influential nodes based on the seed set found for previous social network instead of constructing the solution from an empty set. As similarity in network structure leads to similar set of nodes that maximize the influence.
- In our UBI algorithm, we start from the seed set maximizing the influence under previous social network. Then we change the nodes in the existing set one by one in order to increase the influence under the current social network. As the optimal seed set differs only in a small number of nodes, a few rounds of node exchanges are enough to discover a seed set with large joint influence under current social network.

__ADVANTAGES OF PROPOSED SYSTEM:__- We explore the Influential Node Tracking (INT) problem as an extension to the traditional Influence Maximization problem to maximize the influence coverage under a dynamic social network.
- We propose an efficient algorithm, Upper Bound Interchange (UBI) to solve the INT problem. Our algorithm achieves comparable results as hill-climbing greedy algorithm approximation is guaranteed. The algorithm has the time complexity of O(kn), and the space complexity of O(n), where n is the number of nodes and k is the size of the seed set.
- We propose an algorithm UBI+, based on UBI, that improves the computation of node replacement upper bound.
- We evaluate the performance on large-scale real social network. The experiment results confirm our theoretical findings and show that our UBI and UBI+ algorithm achieve better performance of both influence coverage and running time.

__SYSTEM REQUIREMENTS:__

__HARDWARE REQUIREMENTS:__

- System : Pentium Dual Core.
- Hard Disk : 120 GB.
- Monitor : 15’’ LED
- Input Devices : Keyboard, Mouse
- Ram : 1 GB

__SOFTWARE REQUIREMENTS:__

- Operating system : Windows 7.
- Coding Language : JAVA/J2EE
- Tool : Eclipse Luna
- Database : MYSQL

__REFERENCE:__
Guojie Song, Yuanhao Li, Xiaodong Chen, and Xinran He, “Influential Node Tracking on Dynamic Social Network: An Interchange Greedy Approach”, IEEE Transactions on Knowledge and Data Engineering, 2017.