human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "solving np complete problems with delayed signals an overview of current research directions"):
  Abstract: In this paper we summarize the existing principles for building unconventional computing devices that involve delayed signals for encoding solutions to NP-complete problems. We are interested in the following aspects: the properties of the signal, the operations performed within the devices, some components required for the physical implementation, precision required for correctly reading the solution and the decrease in the signal's strength. Six problems have been solved so far by using the above enumerated principles: Hamiltonian path, travelling salesman, bounded and unbounded subset sum, Diophantine equations and exact cover. For the hardware implementation several types of signals can be used: light, electric power, sound, electro-magnetic etc.

Includes members:
  Member "solving the subset sum problem with a light based device":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "a scalable photonic computer solving the subset sum problem")
  Member "solving the hamiltonian path problem with a light based computer":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "memcomputing np complete problems in polynomial time using polynomial resources and collective states")
  Member "exact cover with light":
    also connected through other hyperedges:
      (none)

Question: Please tell me which class the source paper 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.ET(Emerging Technologies)