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: "upper bound on the capacity of the nonlinear schr odinger channel"
  Abstract: It is shown that the capacity of the channel modeled by (a discretized version of) the stochastic nonlinear Schr\"odinger (NLS) equation is upper-bounded by $\log(1+\text{SNR})$ with $\text{SNR}=\mathcal P_0/\sigma^2(z)$, where $\mathcal P_0$ is the average input signal power and $\sigma^2(z)$ is the total noise power up to distance $z$. The result is a consequence of the fact that the deterministic NLS equation is a Hamiltonian energy-preserving dynamical system.

Connected through hyperedge HE-1 (induced by source paper "a signal space distance measure for nondispersive optical fiber"):
  with members:
    - "towards a non stochastic information theory"
    - "autocorrelation function for dispersion free fiber channels with distributed amplification"
    - "fast numerical nonlinear fourier transforms"
    - "information transmission using the nonlinear fourier transform part iii spectrum modulation"
    - "design of apsk constellations for coherent optical channels with nonlinear phase noise"
    - "a nonstochastic information theory for communication and state estimation"
    - "optimizing constellations for single subcarrier intensity modulated optical systems"
    - "on the per sample capacity of nondispersive optical fibers"

Connected through hyperedge HE-2 (induced by source paper "capacity lower bounds of the noncentral chi channel with applications to soliton amplitude modulation"):
  with members:
    - "performance prediction of nonbinary forward error correction in optical transmission experiments"
    - "nonlinear frequency division multiplexing"
    - "nonlinear frequency division multiplexing in the focusing regime"
    - "a lower bound on the per soliton capacity of the nonlinear optical fibre channel"
    - "upper bound on the capacity of a cascade of nonlinear and noisy channels"
    - "fast numerical nonlinear fourier transforms"
    - "information transmission using the nonlinear fourier transform part ii numerical methods"
    - "information transmission using the nonlinear fourier transform part i mathematical tools"

Connected through hyperedge HE-3 (induced by source paper "the asymptotic capacity of the optical fiber"):
  with members:
    - "nonlinear frequency division multiplexing"
    - "models and information rates for multiuser optical fiber channels with nonlinearity and dispersion"
    - "conditions for a monotonic channel capacity"
    - "upper bound on the capacity of a cascade of nonlinear and noisy channels"
    - "information transmission using the nonlinear fourier transform part ii numerical methods"
    - "information transmission using the nonlinear fourier transform part i mathematical tools"
    - "information transmission using the nonlinear fourier transform part iii spectrum modulation"
    - "transmission of information via the non linear scroedinger equation the random gaussian input case"

Connected through hyperedge HE-4 (induced by source paper "a lower bound on the per soliton capacity of the nonlinear optical fibre channel"):
  with members:
    - "upper bound on the capacity of a cascade of nonlinear and noisy channels"
    - "capacity of a nonlinear optical channel with finite memory"
    - "information transmission using the nonlinear fourier transform part ii numerical methods"
    - "information transmission using the nonlinear fourier transform part i mathematical tools"
    - "information transmission using the nonlinear fourier transform part iii spectrum modulation"
    - "on the achievable communication rates of generalized soliton transmission systems"

Connected through hyperedge HE-5 (induced by source paper "rates achievable on a fiber optical split step fourier channel"):
  with members:
    - "improved lower bounds on mutual information accounting for nonlinear signal noise interaction"
    - "conditions for a monotonic channel capacity"
    - "upper bound on the capacity of a cascade of nonlinear and noisy channels"

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)