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 "a survey of symbolic methods for establishing equivalence based properties in cryptographic protocols"):
  Abstract: Cryptographic protocols aim at securing communications over insecure networks such as the Internet, where dishonest users may listen to communications and interfere with them. A secure communication has a different meaning depending on the underlying application. It ranges from the confidentiality of a data to e.g. verifiability in electronic voting systems. Another example of a security notion is privacy. #R##N#Formal symbolic models have proved their usefulness for analysing the security of protocols. Until quite recently, most results focused on trace properties like confidentiality or authentication. There are however several security properties, which cannot be defined (or cannot be naturally defined) as trace properties and require a notion of behavioural equivalence. Typical examples are anonymity, and privacy related properties. During the last decade, several results and verification tools have been developed to analyse equivalence-based security properties. #R##N#We propose here a synthesis of decidability and undecidability results for equivalence-based security properties. Moreover, we give an overview of existing verification tools that may be used to verify equivalence-based security properties.

Includes members:
  Member "partial order reduction for security protocols":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "por for security protocol equivalences beyond action determinism")
  Member "a reduced semantics for deciding trace equivalence using constraint systems":
    also connected through other hyperedges:
      (none)
  Member "psi calculi a framework for mobile processes with nominal data and logic":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "a formal approach to the engineering of domain specific distributed systems")
  Member "yapa a generic tool for computing intruder knowledge":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "the applied pi calculus mobile values new names and secure communication")
  Member "a trace based bisimulation for the spi calculus":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "elementary deduction problem for locally stable theories with normal forms")

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.CR(Cryptography and Security)