human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "towards improving christofides algorithm for half integer tsp"
  Abstract: We study the traveling salesman problem (TSP) in the case when the objective function of the subtour linear programming relaxation is minimized by a half-cycle point: $x_e \in \{ 0 ,1/2 , 1 \}$ where the half-edges form a 2-factor and the 1-edges form a perfect matching. Such points are sufficient to resolve half-integer TSP in general and they have been conjectured to demonstrate the largest integrality gap for the subtour relaxation. #R##N#For half-cycle points, the best-known approximation guarantee is $3/2$ due to Christofides famous algorithm. Proving an integrality gap of $\alpha$ for the subtour relaxation is equivalent to showing that $\alpha x$ can be written as a convex combination of tours, where $x$ is any feasible solution for this relaxation. To beat Christofides bound, our goal is to show that $(2-\epsilon)x$ can be written as a convex combination of tours for some positive constant $\epsilon$. Let $y_e = 2-\epsilon$ when $x_e=1$ and $y_e= 3/4$ when $x_e = 1/2$. As a first step towards this goal, our main result is to show that $y$ can be written as a convex combination of tours. In other words, we show that we can save on 1-edges, which has several applications. Among them, it gives an alternative algorithm for the recently studied uniform cover problem. Our main new technique is a procedure to glue tours over proper 3-edge cuts that are tight with respect to $x$ , thus reducing the problem to a base case in which such cuts do not occur.

Connected through hyperedge HE-1 (induced by source paper "an improved approximation algorithm for tsp in the half integral case"):
  with members:
    - "cover and conquer augmenting decompositions for connectivity problems"
    - "improved inapproximability for tsp"
    - "13 9 approximation for graphic tsp"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.DS(Data Structures and Algorithms)