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: "optimal selection of spectrum sensing duration for an energy harvesting cognitive radio"
  Abstract: In this paper, we consider a time-slotted cognitive radio (CR) setting with buffered and energy harvesting primary and CR users. At the beginning of each time slot, the CR user probabilistically chooses the spectrum sensing duration from a predefined set. If the primary user (PU) is sensed to be inactive, the CR user accesses the channel immediately. The CR user optimizes the sensing duration probabilities in order to maximize its mean data service rate with constraints on the stability of the primary and cognitive queues. The optimization problem is split into two subproblems. The first is a linear-fractional program, and the other is a linear program. Both subproblems can be solved efficiently.

Connected through hyperedge HE-1 (induced by source paper "cooperative cognitive radio network with energy harvesting stability analysis"):
  with members:
    - "cooperative access in cognitive radio networks stable throughput and delay tradeoffs"

Connected through hyperedge HE-2 (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"
    - "on the coexistence of a primary user with an energy harvesting secondary user a case of cognitive cooperation"
    - "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-3 (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"
    - "on the coexistence of a primary user with an energy harvesting secondary user a case of cognitive cooperation"
    - "opportunistic wireless energy harvesting in cognitive radio networks"
    - "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-4 (induced by source paper "power optimal feedback based random spectrum access for an energy harvesting cognitive user"):
  with members:
    - "harvest then cooperate wireless powered cooperative communications"
    - "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"
    - "cognitive interference management in retransmission based wireless networks"
    - "optimum transmission policies for battery limited energy harvesting nodes"
    - "optimal packet scheduling in an energy harvesting communication system"
    - "optimal energy management policies for energy harvesting sensor nodes"

Connected through hyperedge HE-5 (induced by source paper "optimal random access and random spectrum sensing for an energy harvesting cognitive radio with and without primary feedback leveraging"):
  with members:
    - "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"
    - "cognitive interference management in retransmission based wireless networks"
    - "optimum transmission policies for battery limited energy harvesting nodes"
    - "optimal energy management policies for energy harvesting sensor nodes"

Connected through hyperedge HE-6 (induced by source paper "maximum throughput of a cooperative energy harvesting cognitive radio user"):
  with members:
    - "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"

Connected through hyperedge HE-7 (induced by source paper "on the coexistence of a primary user with an energy harvesting secondary user a case of cognitive cooperation"):
  with members:
    - "harvest then cooperate wireless powered cooperative communications"
    - "energy efficiency evaluation of cellular networks based on spatial distributions of traffic load and power consumption"
    - "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"
    - "optimum transmission policies for battery limited energy harvesting nodes"
    - "optimal packet scheduling in an energy harvesting communication system"
    - "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.NI(Networking and Internet Architecture)