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: "promises and challenges of ambient assisted living systems"
  Abstract: The population of elderly people keeps increasing rapidly, which becomes a predominant aspect of our societies. As such, solutions both efficacious and cost-effective need to be sought. Ambient Assisted Living (AAL) is a new approach which promises to address the needs from elderly people. Ambient Intelligence technologies are widely developed in this domain aiming to construct safe environments around assisted peoples and help them maintain independent living. However, there are still many fundamental issues in AAL that remain open. Most of the current efforts still do not fully express the power of human being, and the importance of social connections and social activities is less noticed. Our conjecture is that such features are fundamental prerequisites towards truly effective AAL services. This paper reviews the current status of researches on AAL, discusses the promises and possible advantages of AAL, and also indicates the challenges we must meet in order to develop practical and efficient AAL systems for elderly people. In this paper, we also propose an approach to construct effective home-care system for the elderly people.

Connected through hyperedge HE-1 (induced by source paper "overview and challenges of ambient systems towards a constructivist approach to their modelling"):
  with members:
    - "analysis and observations from the first amazon picking challenge"

Connected through hyperedge HE-2 (induced by source paper "service oriented communities visions and contributions towards social organizations"):
  with members:
    - "a design tool to reason about ambient assisted living systems"
    - "on the requirements of new software development"
    - "a service oriented infrastructure approach for mutual assistance communities"
    - "the missing ones key ingredients towards effective ambient assisted living systems"
    - "participant a new concept for optimally assisting the elder people"

Connected through hyperedge HE-3 (induced by source paper "the missing ones key ingredients towards effective ambient assisted living systems"):
  with members:
    - "a design tool to reason about ambient assisted living systems"
    - "a service oriented infrastructure approach for mutual assistance communities"
    - "participant a new concept for optimally assisting the elder people"

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.CY(Computers and Society)