Dual Contrastive Attributed Graph Clustering Network

Attributed graph clustering is one of the most important tasks in graph analysis field, the goal of which is to group nodes with similar representations into the same cluster without manual guidance. Recent studies based on graph contrastive learning have achieved impressive results in processing graph-structured data. However, existing graph contrastive learning based methods 1) do not directly address the clustering task, since the representation learning and clustering process are separated; 2) depend too much on graph data augmentation, which greatly limits the capability of contrastive learning; 3) ignore the contrastive message for subspace clustering. To accommodate the aforementioned issues, we propose a generic framework called Dual Contrastive Attributed Graph Clustering Network (DCAGC). In DCAGC, by leveraging Neighborhood Contrast Module, the similarity of the neighbor nodes will be maximized and the quality of the node representation will be improved. Meanwhile, the Contrastive Self-Expression Module is built by minimizing the node representation before and after the reconstruction of the self-expression layer to obtain a discriminative self-expression matrix for spectral clustering. All the modules of DCAGC are trained and optimized in a unified framework, so the learned node representation contains clustering-oriented messages. Extensive experimental results on four attributed graph datasets show the superiority of DCAGC compared with 16 state-of-the-art clustering methods. The code of this paper is available at https://github.com/wangtong627/Dual-Contrastive-Attributed-Graph-Clustering-Network.

Evolutionary Computation plus Dynamic Programming for the Bi-Objective Travelling Thief Problem

This research proposes a novel indicator-based hybrid evolutionary approach that combines approximate and exact algorithms. We apply it to a new bi-criteria formulation of the travelling thief problem, which is known to the Evolutionary Computation community as a benchmark multi-component optimisation problem that interconnects two classical NP-hard problems: the travelling salesman problem and the 0-1 knapsack problem. Our approach employs the exact dynamic programming algorithm for the underlying Packing-While-Travelling (PWT) problem as a subroutine within a bi-objective evolutionary algorithm. This design takes advantage of the data extracted from Pareto fronts generated by the dynamic program to achieve better solutions. Furthermore, we develop a number of novel indicators and selection mechanisms to strengthen synergy of the two algorithmic components of our approach. The results of computational experiments show that the approach is capable to outperform the state-of-the-art results for the single-objective case of the problem.

Exact Approaches for the Travelling Thief Problem

Many evolutionary and constructive heuristic approaches have been introduced in order to solve the Traveling Thief Problem (TTP). However, the accuracy of such approaches is unknown due to their inability to find global optima. In this paper, we propose three exact algorithms and a hybrid approach to the TTP. We compare these with state-of-the-art approaches to gather a comprehensive overview on the accuracy of heuristic methods for solving small TTP instances.