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: "sorting networks to the end and back again"
  Abstract: Abstract   New properties of the front and back ends of sorting networks are studied, illustrating their utility when searching for bounds on optimal networks. Search focuses first on the “out-sides” of the network and then on the inner part. Previous works focused on properties of the front end to break symmetries in the search. The new, out-side-in, properties shed understanding on how sorting networks sort, and facilitate the computation of new bounds on optimality. We present new, faster, parallel sorting networks for 17–20 inputs. For 17 inputs, we show that no sorting network using less layers exists.

Connected through hyperedge HE-1 (induced by source paper "enhanced optimization with composite objectives and novelty selection"):
  with members:
    - "discovering evolutionary stepping stones through behavior domination"
    - "robots that can adapt like animals"
    - "illuminating search spaces by mapping elites"
    - "the quest for optimal sorting networks efficient generation of two layer prefixes"
    - "evolution of swarm robotics systems with novelty search"

Connected through hyperedge HE-2 (induced by source paper "joint size and depth optimization of sorting networks"):
  with members:
    - "new bounds on optimal sorting networks"
    - "optimal sorting networks"

Connected through hyperedge HE-3 (induced by source paper "sat encodings for sorting networks single exception sorting networks and e halvers"):
  with members:
    - "new bounds on optimal sorting networks"
    - "zig zag sort a simple deterministic data oblivious sorting algorithm running in o n log n time"

Connected through hyperedge HE-4 (induced by source paper "optimal depth sorting networks"):
  with members:
    - "solving and verifying the boolean pythagorean triples problem via cube and conquer"
    - "new bounds on optimal sorting networks"
    - "computing the ramsey number r 4 3 3 using abstraction and symmetry breaking"
    - "applying sorting networks to synthesize optimized sorting libraries"
    - "sorting networks the end game"
    - "the quest for optimal sorting networks efficient generation of two layer prefixes"
    - "twenty five comparators is optimal when sorting nine inputs and twenty nine for ten"
    - "computer aided proof of erdos discrepancy properties"

Connected through hyperedge HE-5 (induced by source paper "an improved subsumption testing algorithm for the optimal size sorting network problem"):
  with members:
    - "new bounds on optimal sorting networks"
    - "the quest for optimal sorting networks efficient generation of two layer prefixes"
    - "twenty five comparators is optimal when sorting nine inputs and twenty nine for ten"
    - "optimal sorting networks"

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)