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: "error rates of the maximum likelihood detector for arbitrary constellations convex concave behavior and applications"
  Abstract: Motivated by a recent surge of interest in convex optimization techniques, convexity/concavity properties of error rates of the maximum likelihood detector operating in the AWGN channel are studied and extended to frequency-flat slow-fading channels. Generic conditions are identified under which the symbol error rate (SER) is convex/concave for arbitrary multidimensional constellations. In particular, the SER is convex in SNR for any one- and two-dimensional constellation, and also in higher dimensions at high SNR. Pairwise error probability and bit error rate are shown to be convex at high SNR, for arbitrary constellations and bit mapping. Universal bounds for the SER first and second derivatives are obtained, which hold for arbitrary constellations and are tight for some of them. Applications of the results are discussed, which include optimum power allocation in spatial multiplexing systems, optimum power/time sharing to decrease or increase (jamming problem) error rate, an implication for fading channels (?fading is never good in low dimensions?) and optimization of a unitary-precoded OFDM system. For example, the error rate bounds of a unitary-precoded OFDM system with QPSK modulation, which reveal the best and worst precoding, are extended to arbitrary constellations, which may also include coding. The reported results also apply to the interference channel under Gaussian approximation, to the bit error rate when it can be expressed or approximated as a nonnegative linear combination of individual symbol error rates, and to coded systems.

Connected through hyperedge HE-1 (induced by source paper "on convexity of error rates in digital communications"):
  with members:
    - "error rates of capacity achieving codes are convex"
    - "bit error rate is convex at high snr"
    - "on node density outage probability tradeoff in wireless networks"
    - "log concavity property of the error probability with application to local bounds for wireless communications"
    - "on optimum power allocation for the v blast"
    - "symbol error rates of maximum likelihood detector convex concave behavior and applications"

Connected through hyperedge HE-2 (induced by source paper "a new representation for the symbol error rate"):
  with members:
    - "on the symbol error probability of regular polytopes"
    - "applications of stochastic ordering to wireless communications"

Connected through hyperedge HE-3 (induced by source paper "secure diversity multiplexing tradeoff of zero forcing transmit scheme at finite snr"):
  with members:
    - "secure transmission with multiple antennas ii the mimome wiretap channel"
    - "secure communication in the low snr regime a characterization of the energy secrecy tradeoff"
    - "the secrecy capacity region of the gaussian mimo multi receiver wiretap channel"
    - "on the throughput of secure hybrid arq protocols for gaussian block fading channels"
    - "diversity multiplexing tradeoff for the multiple antenna wire tap channel"
    - "log concavity property of the error probability with application to local bounds for wireless communications"
    - "impact of spatial correlation on the finite snr diversity multiplexing tradeoff"
    - "the secrecy capacity of the mimo wiretap channel"

Connected through hyperedge HE-4 (induced by source paper "applications of stochastic ordering to wireless communications"):
  with members:
    - "on certain large random hermitian jacobi matrices with applications to wireless communications"
    - "monotonicity results for coherent mimo rician channels"

Connected through hyperedge HE-5 (induced by source paper "error rates of capacity achieving codes are convex"):
  with members:
    - "on optimum power allocation for the v blast"
    - "symbol error rates of maximum likelihood detector convex concave behavior and applications"

Connected through hyperedge HE-6 (induced by source paper "bit error rate is convex at high snr"):
  with members:
    - "log concavity property of the error probability with application to local bounds for wireless communications"
    - "on optimum power allocation for the v blast"

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)