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: "functional dependencies with null markers"
  Abstract: Functional dependencies (FDs) are an integral part of database design. However, they are only defined when we exclude null markers. However, we commonly use null markers in practice. To bridge this gap between theory and practice, researchers have proposed definitions of FDs over relations with null markers. Though sound, these definitions lack some qualities that we find desirable. For example, some fail to satisfy Armstrong's axioms—while these axioms are part of the foundation of common database methodologies. We propose a set of properties that any extension of FDs over relations with null markers should possess. We then propose two new extensions having these properties. These extensions attempt to allow null markers where they make sense to practitioners. They both support Armstrong's axioms and provide realizable null markers: at any time, some or all of the null markers can be replaced by actual values without causing an anomaly. Our proposals may improve database designs.

Connected through hyperedge HE-1 (induced by source paper "on desirable semantics of functional dependencies over databases with incomplete information"):
  with members:
    - "using fuzzy logic to evaluate normalization completeness for an improved database design"
    - "a call to arms revisiting database design"

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.DB(Databases)