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: "a retrial system with two input streams and two orbit queues"
  Abstract: Two independent Poisson streams of jobs flow into a single-server service system having a limited common buffer that can hold at most one job. If a type-i job (i=1,2) finds the server busy, it is blocked and routed to a separate type-i retrial (orbit) queue that attempts to re-dispatch its jobs at its specific Poisson rate. This creates a system with three dependent queues. Such a queueing system serves as a model for two competing job streams in a carrier sensing multiple access system. We study the queueing system using multi-dimensional probability generating functions, and derive its necessary and sufficient stability conditions while solving a boundary value problem. Various performance measures are calculated and numerical results are presented.

Connected through hyperedge HE-1 (induced by source paper "performance analysis of a cooperative wireless network with adaptive relays"):
  with members:
    - "network level cooperation in random access iot networks with aggregators"
    - "stable throughput and delay analysis of a random access network with queue aware transmission"
    - "wireless network level partial relay cooperation a stable throughput analysis"
    - "random access in c ran for user activity detection with limited capacity fronthaul"
    - "relay assisted multiple access with full duplex multi packet reception"
    - "analysis of an offloading scheme for data centers in the framework of fog computing"
    - "network level performance evaluation of a two relay cooperative random access wireless system"
    - "network level cooperation in energy harvesting wireless networks"

Connected through hyperedge HE-2 (induced by source paper "stable throughput and delay analysis of a random access network with queue aware transmission"):
  with members:
    - "random access in c ran for user activity detection with limited capacity fronthaul"
    - "on frame asynchronous coded slotted aloha asymptotic finite length and delay analysis"
    - "relay assisted multiple access with full duplex multi packet reception"
    - "random access protocols with collision resolution in a noncoherent setting"
    - "aloha random access that operates as a rateless code"
    - "asymptotic stability region of slotted aloha"

Connected through hyperedge HE-3 (induced by source paper "performance analysis of a cooperative wireless network with adaptive relays a network level study"):
  with members:
    - "random access in c ran for user activity detection with limited capacity fronthaul"
    - "relay assisted multiple access with full duplex multi packet reception"
    - "stability and performance issues of a relay assisted multiple access scheme with mpr capabilities"
    - "network level performance evaluation of a two relay cooperative random access wireless system"

Connected through hyperedge HE-4 (induced by source paper "the chaos of propagation in a retrial supermarket model"):
  with members:
    - "a matrix analytic solution for randomized load balancing models with phase type service times"
    - "super exponential solution in markovian supermarket models framework and challenge"
    - "mean field for markov decision processes from discrete to continuous optimization"

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)