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: "on the coexistence of a primary user with an energy harvesting secondary user a case of cognitive cooperation"
  Abstract: In this paper, we consider a cognitive scenario where an energy harvesting secondary user (SU) shares the spectrum with a primary user (PU). The secondary source helps the primary source in delivering its undelivered packets during periods of silence of the primary source. The primary source has a queue for storing its data packets, whereas the secondary source has two data queues; a queue for storing its own packets and the other for storing the fraction of the undelivered primary packets accepted for relaying. The secondary source is assumed to be a battery-based node which harvests energy packets from the environment. In addition to its data queues, the SU has an energy queue to store the harvested energy packets. The secondary energy packets are used for primary packets decoding and data packets transmission. More specifically, if the secondary energy queue is empty, the secondary source can neither help the primary source nor transmit a packet from the data queues. The energy queue is modeled as a discrete time queue with Markov arrival and service processes. Due to the interaction of the queues, we provide inner and outer bounds on the stability region of the proposed system. We investigate the impact of the energy arrival rate on the stability region. Numerical results show the significant gain of cooperation.

Connected through hyperedge HE-1 (induced by source paper "optimal spectrum access for a rechargeable cognitive radio user based on energy buffer state"):
  with members:
    - "dynamic spectrum access in cognitive radio networks with rf energy harvesting"
    - "on spectrum sharing between energy harvesting cognitive radio users and primary users"
    - "power optimal feedback based random spectrum access for an energy harvesting cognitive user"
    - "optimal selection of spectrum sensing duration for an energy harvesting cognitive radio"
    - "optimal random access and random spectrum sensing for an energy harvesting cognitive radio"
    - "cooperative cognitive relaying with ordered cognitive multiple access"
    - "green cellular networks a survey some research issues and challenges"
    - "optimal utilization of a cognitive shared channel with a rechargeable primary source node"

Connected through hyperedge HE-2 (induced by source paper "on spectrum sharing between energy harvesting cognitive radio users and primary users"):
  with members:
    - "dynamic spectrum access in cognitive radio networks with rf energy harvesting"
    - "opportunistic wireless energy harvesting in cognitive radio networks"
    - "optimal selection of spectrum sensing duration for an energy harvesting cognitive radio"
    - "optimal random access and random spectrum sensing for an energy harvesting cognitive radio"
    - "green cellular networks a survey some research issues and challenges"
    - "optimal utilization of a cognitive shared channel with a rechargeable primary source node"
    - "optimum transmission policies for battery limited energy harvesting nodes"
    - "optimal packet scheduling in an energy harvesting communication system"

Connected through hyperedge HE-3 (induced by source paper "energy efficient cooperative cognitive relaying schemes for cognitive radio networks"):
  with members:
    - "secret key aided scheme for securing untrusted df relaying networks"
    - "low latency ultra reliable 5g communications finite blocklength bounds and coding schemes"
    - "maximum throughput of a secondary user cooperating with an energy aware primary user"
    - "maximum throughput of a cooperative energy harvesting cognitive radio user"

Connected through hyperedge HE-4 (induced by source paper "optimal cooperative cognitive relaying and spectrum access for an energy harvesting cognitive radio reinforcement learning approach"):
  with members:
    - "comments on optimal utilization of a cognitive shared channel with a rechargeable primary source node"
    - "optimal random access and random spectrum sensing for an energy harvesting cognitive radio"
    - "optimal utilization of a cognitive shared channel with a rechargeable primary source node"
    - "optimal energy management policies for energy harvesting sensor nodes"

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.IT(Information Theory)