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: "shortened array codes of large girth"
  Abstract: One approach to designing structured low-density parity-check (LDPC) codes with large girth is to shorten codes with small girth in such a manner that the deleted columns of the parity-check matrix contain all the variables involved in short cycles. This approach is especially effective if the parity-check matrix of a code is a matrix composed of blocks of circulant permutation matrices, as is the case for the class of codes known as array codes. We show how to shorten array codes by deleting certain columns of their parity-check matrices so as to increase their girth. The shortening approach is based on the observation that for array codes, and in fact for a slightly more general class of LDPC codes, the cycles in the corresponding Tanner graph are governed by certain homogeneous linear equations with integer coefficients. Consequently, we can selectively eliminate cycles from an array code by only retaining those columns from the parity-check matrix of the original code that are indexed by integer sequences that do not contain solutions to the equations governing those cycles. We provide Ramsey-theoretic estimates for the maximum number of columns that can be retained from the original parity-check matrix with the property that the sequence of their indices avoid solutions to various types of cycle-governing equations. This translates to estimates of the rate penalty incurred in shortening a code to eliminate cycles. Simulation results show that for the codes considered, shortening them to increase the girth can lead to significant gains in signal-to-noise ratio (SNR) in the case of communication over an additive white Gaussian noise (AWGN) channel

Connected through hyperedge HE-1 (induced by source paper "from cages to trapping sets and codewords a technique to derive tight upper bounds on the minimum size of trapping sets and minimum distance of ldpc codes"):
  with members:
    - "on the minimum stopping distance of array low density parity check codes"
    - "on characterization of elementary trapping sets of variable regular ldpc codes"
    - "practical graph isomorphism ii"
    - "quasi cyclic ldpc codes influence of proto and tanner graph structure on minimum hamming distance upper bounds"
    - "searching for voltage graph based ldpc tailbiting codes with large girth"
    - "error floor approximation for ldpc codes in the awgn channel"
    - "lowering the error floor of ldpc codes using cyclic liftings"
    - "on the dynamics of the error floor behavior in regular ldpc codes"

Connected through hyperedge HE-2 (induced by source paper "array convolutional low density parity check codes"):
  with members:
    - "progressive differences convolutional low density parity check codes"
    - "on a family of circulant matrices for quasi cyclic low density generator matrix codes"
    - "deriving good ldpc convolutional codes from ldpc block codes"
    - "error rate analysis for coded multicarrier systems over quasi static fading channels"

Connected through hyperedge HE-3 (induced by source paper "hierarchical and high girth qc ldpc codes"):
  with members:
    - "quasi cyclic ldpc codes based on pre lifted protographs"
    - "quasi cyclic ldpc codes influence of proto and tanner graph structure on minimum hamming distance upper bounds"
    - "searching for voltage graph based ldpc tailbiting codes with large girth"
    - "threshold saturation via spatial coupling why convolutional ldpc ensembles perform so well over the bec"
    - "lowering the error floor of ldpc codes using cyclic liftings"

Connected through hyperedge HE-4 (induced by source paper "design of multiple edge protographs for qc ldpc codes avoiding short inevitable cycles"):
  with members:
    - "bounds on the minimum distance of punctured quasi cyclic ldpc codes"
    - "quasi cyclic ldpc codes influence of proto and tanner graph structure on minimum hamming distance upper bounds"
    - "searching for voltage graph based ldpc tailbiting codes with large girth"
    - "pseudocodewords of tanner graphs"

Connected through hyperedge HE-5 (induced by source paper "decomposition methods for large scale lp decoding"):
  with members:
    - "hierarchical and high girth qc ldpc codes"
    - "counting in graph covers a combinatorial characterization of the bethe entropy function"
    - "online alternating direction method"
    - "error floor approximation for ldpc codes in the awgn channel"
    - "improved linear programming decoding of ldpc codes and bounds on the minimum and fractional distance"
    - "l1 projections with box constraints"
    - "efficient implementation of linear programming decoding"
    - "probabilistic analysis of linear programming decoding"

Connected through hyperedge HE-6 (induced by source paper "the cycle consistency matrix approach to absorbing sets in separable circulant based ldpc codes"):
  with members:
    - "design of finite length irregular protograph codes with low error floors over the binary input awgn channel using cyclic liftings"
    - "absorbing set spectrum approach for practical code design"
    - "cyclic and quasi cyclic ldpc codes on row and column constrained parity check matrices and their trapping sets"
    - "lowering the error floor of ldpc codes using cyclic liftings"
    - "structured ldpc codes from permutation matrices free of small trapping sets"

Connected through hyperedge HE-7 (induced by source paper "searching for voltage graph based ldpc tailbiting codes with large girth"):
  with members:
    - "threshold saturation via spatial coupling why convolutional ldpc ensembles perform so well over the bec"
    - "woven graph codes asymptotic performances and examples"
    - "girth 12 quasi cyclic ldpc codes with consecutive lengths"
    - "distance properties of expander codes"

Connected through hyperedge HE-8 (induced by source paper "scalable constructions of fractional repetition codes in distributed storage systems"):
  with members:
    - "fractional repetition codes for repair in distributed storage systems"
    - "network coding for distributed storage systems"

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)