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: "complex additive geometric multilevel solvers for helmholtz equations on spacetrees"
  Abstract: We introduce a family of implementations of low-order, additive, geometric multilevel solvers for systems of Helmholtz equations arising from Schrodinger equations. Both grid spacing and arithmetics may comprise complex numbers, and we thus can apply complex scaling to the indefinite Helmholtz operator. Our implementations are based on the notion of a spacetree and work exclusively with a finite number of precomputed local element matrices. They are globally matrix-free.   Combining various relaxation factors with two grid transfer operators allows us to switch from additive multigrid over a hierarchical basis method into a Bramble-Pasciak-Xu (BPX)-type solver, with several multiscale smoothing variants within one code base. Pipelining allows us to realize full approximation storage (FAS) within the additive environment where, amortized, each grid vertex carrying degrees of freedom is read/written only once per iteration. The codes realize a single-touch policy. Among the features facilitated by matrix-free FAS is arbitrary dynamic mesh refinement (AMR) for all solver variants. AMR as an enabler for full multigrid (FMG) cycling—the grid unfolds throughout the computation—allows us to reduce the cost per unknown.   The present work primary contributes toward software realization and design questions. Our experiments show that the consolidation of single-touch FAS, dynamic AMR, and vectorization-friendly, complex scaled, matrix-free FMG cycles delivers a mature implementation blueprint for solvers of Helmholtz equations in general. For this blueprint, we put particular emphasis on a strict implementation formalism as well as some implementation correctness proofs.

Connected through hyperedge HE-1 (induced by source paper "the peano software parallel automaton based dynamically adaptive grid traversals"):
  with members:
    - "stop talking to me a communication avoiding ader dg realisation"
    - "quasi matrix free hybrid multigrid on dynamically adaptive cartesian grids"
    - "two particle in grid realisations on spacetrees"
    - "algebraic geometric matrix free multigrid on dynamically adaptive cartesian meshes"
    - "how many three dimensional hilbert curves are there"
    - "morton curve segments produce no more than two distinct face connected subdomains"
    - "bounds on the number of discontinuities of morton type space filling curves"
    - "a survey of high level frameworks in block structured adaptive mesh refinement packages"

Connected through hyperedge HE-2 (induced by source paper "non conforming mesh refinement for high order finite elements"):
  with members:
    - "recursive algorithms for distributed forests of octrees"
    - "support for non conformal meshes in petsc s dmplex interface"
    - "mesh algorithms for pde with sieve i mesh distribution"

Connected through hyperedge HE-3 (induced by source paper "quasi matrix free hybrid multigrid on dynamically adaptive cartesian grids"):
  with members:
    - "multi dimensional intra tile parallelization for memory starved stencil computations"

Connected through hyperedge HE-4 (induced by source paper "a multigrid solver to the helmholtz equation with a point source based on travel time and amplitude"):
  with members:
    - "full waveform inversion guided by travel time tomography"
    - "jinv a flexible julia package for pde parameter estimation"
    - "a fast marching algorithm for the factored eikonal equation"
    - "julia a fresh approach to numerical computing"
    - "a parallel sweeping preconditioner for heterogeneous 3d helmholtz equations"

Connected through hyperedge HE-5 (induced by source paper "full waveform inversion guided by travel time tomography"):
  with members:
    - "a fast marching algorithm for the factored eikonal equation"
    - "a parallel sweeping preconditioner for heterogeneous 3d helmholtz equations"

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.MS(Mathematical Software)