Routing among Convex Polygonal Obstacles in the Plane -- Target Coverage with Minimized Number of Camera Sensors -- Two-Stage Submodular Maximization under Curvature -- An Improved Approximation Algorithm for Capacitated Correlation Clustering Problem -- The Selection of COVID-19 Epidemic Prevention and Control Programs Based on Group Decision Making -- Which Option is a Better Way to Improve Transfer Learning Performance ? -- On Maximizing the Difference between an Approximately Submodular Function and a Linear Function Subject to a Matroid Constraint -- On Various Open-End Bin Packing Game -- A Linear-Time Streaming Algorithm for Cardinality-Constrained Maximizing Monotone Non-submodular Set Functions -- Approximation Algorithms for Two Parallel Dedicated Machine Scheduling with Conflict Constraints -- Computing the One-Visibility Cop-Win Strategies for Trees -- Complexity and Approximation Results on the Shared Transportation Problem -- The complexity of finding optimal subgraphs to represent spatial correlation -- New Approximation Algorithms for the Rooted Budgeted Cycle Cover Problem -- Evolutionary Equilibrium Analysis for Decision on Block Size in Blockchain Systems -- Efficient Algorithms for Scheduling Parallel Jobs with Interval Constraints in Clouds -- Two-Stage Stochastic Max-Weight Independent Set Problems -- Routing and Scheduling Problems with Two Agents on a Line-Shaped Network -- The Price of Anarchy of Generic Valid Utility Systems -- Single Machine Scheduling with Rejection and Generalized Parameters -- Approximation Algorithm and Hardness Results for Defensive Domination in Graphs -- An Improved Physical ZKP for Nonogram -- Finding All Leftmost Separators of Size $\leq k$ -- Maximize the Probability of Union-Influenced in Social Networks -- A Novel Algorithm for Max Sat Calling MOCE to Order -- The Smallest Number of Vertices in a 2-Arc-Strong Digraph without Pair of Arc-Disjoint in- and out-Branchings -- Generalized Self-Profit Maximization in Attribute Networks -- Parameterized Complexity Classes Defined by Threshold Circuits: Using Sorting Networks to Show Collapses with W-Hierarchy Classes -- Maximization of Monotone Non-Submodular Functions with a Knapsack Constraint over the Integer Lattice -- Sublinear-time Reductions for Big Data Computing -- Capacitated Partial Inverse Maximum Spanning Tree under the Weighted $l_{\infty}$-Norm -- Approximation Algorithms for Some Min-Max and Minimum Stacker Crane Cover Problems -- Succinct Data Structures for SP, Block-Cactus and 3-Leaf Power Graphs -- Streaming Submodular Maximization under Differential Privacy Noise -- Online Bottleneck Semi-Matching -- Optimal Due Date Assignment without Restriction and Convex Resource Allocation in Group Technology Scheduling -- Constrained Stable Marriage with Free edges or Few Blocking Pairs -- Backgammon is Hard -- Two-Facility Location Games with a Minimum Distance Requirement on a Circle -- Open Shop Scheduling Problem with a Non-Resumable Flexible Maintenance Period -- Parallel Algorithm For Minimum Partial Dominating Set In Unit Disk Graph -- An Improved Approximation Algorithm for Squared Metric k-Facility Location -- Parameterized Algorithms for Linear Layouts of Graphs with Respect to the Vertex Cover Number -- The Fractional k-Truncated Metric Dimension of Graphs -- On Structural Parameterizations of the Offensive Alliance Problem -- On the k-colored Rainbow Sets in Fixed Dimensions -- Cycle-Connected Mixed Graphs and Related Problems -- Directed width parameters on semicomplete digraphs -- Improved Parameterized Approximation for Balanced k-Median -- A LP-Based Approximation Algorithm for Generalized Traveling Salesperson Path Problem -- Hardness Results of Connected Power Domination for Bipartite Graphs and Chordal Graphs -- Approximation Algorithm for Min-Max Correlation Clustering Problem with Outliers -- Delay-Constrained Minimum Shortest Path Trees and Related Problems -- On the Feedback Number of 3-Uniform Linear Extremal Hypergraph -- A Multi-Pass Streaming Algorithm for Regularized Submodular Maximization.

This book constitutes the refereed proceedings of the 15th Annual International Conference on Combinatorial Optimization and Applications, COCOA 2021, which took place in Tianjin, China, during December 17-19, 2021. The 55 papers presented in this volume were carefully reviewed and selected from 122 submissions. They deal with combinatorial optimization and its applications in general, focusing on algorithms design, theoretical and experimental analysis, and applied research of general algorithmic interest.