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: "closing the gap for pseudo polynomial strip packing"
  Abstract: We study pseudo-polynomial Strip Packing. Given a set of rectangular axis parallel items and a strip with bounded width and infinite height the objective is to find a packing of the items into the strip which minimizes the packing height. We speak of pseudo-polynomial Strip Packing if we consider algorithms with pseudo-polynomial running time with respect to the width of the strip. It is known that there is no pseudo-polynomial algorithm for Strip Packing with a ratio better than $5/4$ unless $P=NP$. The best algorithm so far has a ratio of $4/3 +\varepsilon$. In this paper, we close this gap: We present an algorithm with approximation ratio $5/4 + \varepsilon$. This algorithm uses a structural result which is the main accomplishment of this paper. This structural result applies to other problem settings as well, which enabled us to present algorithms with approximation ratio $5/4 + \varepsilon$ for Strip Packing with rotations (90 degrees) and Contiguous Moldable Task Scheduling.

Connected through hyperedge HE-1 (induced by source paper "linear time algorithms for multiple cluster scheduling and multiple strip packing"):
  with members:
    - "on integer programming and convolution"
    - "a faster fptas for the unbounded knapsack problem"

Connected through hyperedge HE-2 (induced by source paper "improved pseudo polynomial time approximation for strip packing"):
  with members:
    - "approximating geometric knapsack via l packings"
    - "complexity and inapproximability results for parallel task scheduling and strip packing"
    - "improved approximation for two dimensional strip packing with polynomial bounded width"
    - "approximation schemes for maximum weight independent set of rectangles"

Connected through hyperedge HE-3 (induced by source paper "complexity and inapproximability results for parallel task scheduling and strip packing"):
  with members:
    - "improved pseudo polynomial time approximation for strip packing"
    - "scheduling monotone moldable jobs in linear time"
    - "hardness of approximation for strip packing"
    - "improved approximation for two dimensional strip packing with polynomial bounded width"

Connected through hyperedge HE-4 (induced by source paper "improved approximation for two dimensional strip packing with polynomial bounded width"):
  with members:
    - "improved pseudo polynomial time approximation for strip packing"
    - "complexity and inapproximability results for parallel task scheduling and strip packing"
    - "hardness of approximation for strip packing"

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.DM(Discrete Mathematics)