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: "xtras a field theory inspired xact package for mathematica"
  Abstract: Abstract   We present the tensor computer algebra package  xTras , which provides functions and methods frequently needed when doing (classical) field theory. Amongst others, it can compute contractions, make Ansatze, and solve tensorial equations. It is built upon the tensor computer algebra system  xAct , a collection of packages for Mathematica.    Program summary   Program title:  xTras   Catalogue identifier:  AESH_v1_0   Program summary URL:  http://cpc.cs.qub.ac.uk/summaries/AESH_v1_0.html    Program obtainable from:  CPC Program Library, Queen’s University, Belfast, N. Ireland   Licensing provisions:  GNU General Public License, version 3   No. of lines in distributed program, including test data, etc.:  155 879   No. of bytes in distributed program, including test data, etc.:  565 389   Distribution format:  tar.gz   Programming language:  Mathematica.   Computer:  Any computer running Mathematica 6 or newer.   Operating system:  Linux, Unix, Windows, OS X.   RAM:  100 Mb   Classification:  5.   External routines:  xACT ( www.xact.es )   Subprograms used:        Cat Id  Title  Reference    AEBH_v1_0  xPerm  CPC 179 (2008) 597    ADZK_v2_0  Invar Tensor Package 2.0  CPC 179 (2008) 586        Nature of problem:   Common problems in classical field theory: making Ansatze, computing contractions, solving tensorial equations, etc.   Solution method:   Various (group theory, brute-force, built-in Mathematica functions, etc.)   Running time:   1–60 s

Connected through hyperedge HE-1 (induced by source paper "riemann tensor polynomial canonicalization by graph algebra extension"):
  with members:
    - "xperm fast index canonicalization for tensor computer algebra"
    - "the invar tensor package"
    - "atensor reduce program for tensor simplification"

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.SC(Symbolic Computation)