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: "worst case optimal tree layout in external memory"
  Abstract: Consider laying out a fixed-topology tree of N nodes into external memory with block size B so as to minimize the worst-case number of block memory transfers required to traverse a path from the root to a node of depth D. We prove that the optimal number of memory transfers is $$ \cases{ #R##N#\displaystyle #R##N#\Theta\left( {D \over \lg (1{+}B)} \right) #R##N#& when $D = O(\lg N)$, \cr #R##N#\displaystyle #R##N#\Theta\left( {\lg N \over \lg \left(1{+}{B \lg N \over D}\right)} \right) #R##N#& when $D = \Omega(\lg N)$ and $D = O(B \lg N)$, \cr #R##N#\displaystyle #R##N#\Theta\left( {D \over B} \right) #R##N#& when $D = \Omega(B \lg N)$. #R##N#} $$

Connected through hyperedge HE-1 (induced by source paper "belga b trees"):
  with members:
    - "weighted dynamic finger in binary search trees"
    - "multi finger binary search trees"
    - "the landscape of bounds for binary search trees"
    - "combining binary search trees"
    - "the power and limitations of static binary search trees with lazy finger"
    - "in pursuit of the dynamic optimality conjecture"
    - "the fresh finger property"

Connected through hyperedge HE-2 (induced by source paper "the power and limitations of static binary search trees with lazy finger"):
  with members:
    - "combining binary search trees"
    - "a static optimality transformation with applications to planar point location"

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.DS(Data Structures and Algorithms)