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: "the invar tensor package differential invariants of riemann"
  Abstract: Abstract   The long standing problem of the relations among the scalar invariants of the Riemann tensor is computationally solved for all    6  ⋅   10  23     objects with up to 12 derivatives of the metric. This covers cases ranging from products of up to 6 undifferentiated Riemann tensors to cases with up to 10 covariant derivatives of a single Riemann. We extend our computer algebra system  Invar  to produce within seconds a canonical form for any of those objects in terms of a basis. The process is as follows: (1) an invariant is converted in real time into a canonical form with respect to the permutation symmetries of the Riemann tensor; (2)  Invar  reads a database of more than    6  ⋅   10  5     relations and applies those coming from the cyclic symmetry of the Riemann tensor; (3) then applies the relations coming from the Bianchi identity, (4) the relations coming from commutations of covariant derivatives, (5) the dimensionally-dependent identities for dimension 4, and finally (6) simplifies invariants that can be expressed as product of dual invariants.  Invar  runs on top of the tensor computer algebra systems  xTensor  (for  Mathematica ) and  Canon  (for  Maple ).    Program summary   Program title: Invar Tensor Package v2.0   Catalogue identifier: ADZK_v2_0   Program summary URL:  http://cpc.cs.qub.ac.uk/summaries/ADZK_v2_0.html    Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland   Licensing provisions: Standard CPC licence,  http://cpc.cs.qub.ac.uk/licence/licence.html    No. of lines in distributed program, including test data, etc.: 3 243 249   No. of bytes in distributed program, including test data, etc.: 939   Distribution format: tar.gz   Programming language: Mathematica and Maple   Computer: Any computer running Mathematica versions 5.0 to 6.0 or Maple versions 9 and 11   Operating system: Linux, Unix, Windows XP, MacOS   RAM: 100 Mb   Word size: 64 or 32 bits   Supplementary material: The new database of relations is much larger than that for the previous version and therefore has not been included in the distribution. To obtain the Mathematica and Maple database files click on this link.   Classification: 1.5, 5   Does the new version supersede the previous version?: Yes. The previous version (1.0) only handled algebraic invariants. The current version (2.0) has been extended to cover differential invariants as well.   Nature of problem: Manipulation and simplification of scalar polynomial expressions formed from the Riemann tensor and its covariant derivatives.   Solution method: Algorithms of computational group theory to simplify expressions with tensors that obey permutation symmetries. Tables of syzygies of the scalar invariants of the Riemann tensor.   Reasons for new version: With this new version, the user can manipulate differential invariants of the Riemann tensor. Differential invariants are required in many physical problems in classical and quantum gravity.   Summary of revisions: The database of syzygies has been expanded by a factor of 30. New commands were added in order to deal with the enlarged database and to manipulate the covariant derivative.   Restrictions: The present version only handles scalars, and not expressions with free indices.   Additional comments: The distribution file for this program is over 53 Mbytes and therefore is not delivered directly when download or Email is requested. Instead a html file giving details of how the program can be obtained is sent.   Running time: One second to fully reduce any monomial of the Riemann tensor up to degree 7 or order 10 in terms of independent invariants. The Mathematica notebook included in the distribution takes approximately 5 minutes to run.

Connected through hyperedge HE-1 (induced by source paper "faster tensor canonicalization"):
  with members:
    - "riemann tensor polynomial canonicalization by graph algebra extension"
    - "introduction to redberry a computer algebra system designed for tensor manipulation"
    - "xperm fast index canonicalization for tensor computer algebra"
    - "cadabra a field theory motivated symbolic computer algebra system"

Connected through hyperedge HE-2 (induced by source paper "xtras a field theory inspired xact package for mathematica"):
  with members:
    - "xperm fast index canonicalization for tensor computer algebra"
    - "the invar tensor package"

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)