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: "penalty dual decomposition method for nonsmooth nonconvex optimization"
  Abstract: Many contemporary signal processing, machine learning and wireless communication applications can be formulated as nonconvex nonsmooth optimization problems. Often there is a lack of efficient algorithms for these problems, especially when the optimization variables are nonlinearly coupled in some nonconvex constraints. In this work, we propose an algorithm named penalty dual decomposition (PDD) for these difficult problems and discuss its various applications. The PDD is a double-loop iterative algorithm. Its inner iterations is used to inexactly solve a nonconvex nonsmooth augmented Lagrangian problem via block-coordinate-descenttype methods, while its outer iteration updates the dual variables and/or a penalty parameter. In Part I of this work, we describe the PDD algorithm and rigorously establish its convergence to KKT solutions. In Part II we evaluate the performance of PDD by customizing it to three applications arising from signal processing and wireless communications.

Connected through hyperedge HE-1 (induced by source paper "intelligent reflecting surface enhanced wireless network two timescale beamforming optimization"):
  with members:
    - "joint active and passive beamforming optimization for intelligent reflecting surface assisted swipt under qos constraints"
    - "intelligent reflecting surface with discrete phase shifts channel estimation and passive beamforming"
    - "miso wireless communication systems via intelligent reflecting surfaces"
    - "secure wireless communication via intelligent reflecting surface"
    - "cascaded channel estimation for large intelligent metasurface assisted massive mimo"
    - "capacity characterization for intelligent reflecting surface aided mimo communication"
    - "resource allocation for secure irs assisted multiuser miso systems"
    - "intelligent reflecting surface meets ofdm protocol design and rate maximization"

Connected through hyperedge HE-2 (induced by source paper "efficiency maximization for uav enabled mobile relaying systems with laser charging"):
  with members:
    - "uav positioning and power control for two way wireless relaying"
    - "3d trajectory optimization in rician fading for uav enabled data harvesting"
    - "cellular connected uav uplink association power control and interference coordination"
    - "throughput maximization for laser powered uav wireless communication systems"
    - "secrecy energy efficiency maximization for uav enabled mobile relaying"
    - "securing uav communications via joint trajectory and power control"
    - "cellular enabled uav communication a connectivity constrained trajectory optimization perspective"
    - "throughput maximization for uav enabled wireless powered communication networks"

Connected through hyperedge HE-3 (induced by source paper "an admm based approach to robust array pattern synthesis"):
  with members:
    - "a robust design for miso physical layer multicasting over line of sight channels"
    - "robust adaptive beamforming for general rank signal model with positive semi definite constraint via potdc"
    - "distributed robust multicell coordinated beamforming with imperfect csi an admm approach"

Connected through hyperedge HE-4 (induced by source paper "structured sumcor multiview canonical correlation analysis for large scale data"):
  with members:
    - "efficient algorithms for large scale generalized eigenvector computation and canonical correlation analysis"
    - "globally convergent stochastic optimization for canonical correlation analysis"
    - "a comparison of relaxations of multiset cannonical correlation analysis and applications"

Connected through hyperedge HE-5 (induced by source paper "spectral efficiency optimization for millimeter wave multiuser mimo systems"):
  with members:
    - "hybrid beamforming via the kronecker decomposition for the millimeter wave massive mimo systems"
    - "joint source relay design for full duplex mimo af relay systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"
    - "near optimal hybrid processing for massive mimo systems via matrix decomposition"
    - "hybrid block diagonalization for massive multiuser mimo systems"
    - "mmwave massive mimo based wireless backhaul for the 5g ultra dense network"

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)