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: "a downward collapse within the polynomial hierarchy"
  Abstract: Downward collapse (a.k.a. upward separation) refers to cases where the equality of two larger classes implies the equality of two smaller classes. We provide an unqualified downward collapse result completely within the polynomial hierarchy. In particular, we prove that, for k > 2, if $\psigkone = \psigktwo$ then $\sigmak = \pik = \ph$. We extend this to obtain a more general downward collapse result.

Connected through hyperedge HE-1 (induced by source paper "using the no search easy hard technique for downward collapse"):
  with members:
    - "what s up with downward collapse using the easy hard technique to link boolean and polynomial hierarchy collapses"

Connected through hyperedge HE-2 (induced by source paper "a moment of perfect clarity i the parallel census technique"):
  with members:
    - "what s up with downward collapse using the easy hard technique to link boolean and polynomial hierarchy collapses"

Connected through hyperedge HE-3 (induced by source paper "what s up with downward collapse using the easy hard technique to link boolean and polynomial hierarchy collapses"):
  with members:
    - "unambiguous computation boolean hierarchies and sparse turing complete sets"
    - "downward collapse from a weaker hypothesis"
    - "translating equality downwards"

Connected through hyperedge HE-4 (induced by source paper "query order and the polynomial hierarchy"):
  with members:
    - "what s up with downward collapse using the easy hard technique to link boolean and polynomial hierarchy collapses"
    - "an introduction to query order"
    - "translating equality downwards"

Connected through hyperedge HE-5 (induced by source paper "an introduction to query order"):
  with members:
    - "translating equality downwards"

Connected through hyperedge HE-6 (induced by source paper "downward collapse from a weaker hypothesis"):
  with members:
    - "what s up with downward collapse using the easy hard technique to link boolean and polynomial hierarchy collapses"
    - "an introduction to query order"
    - "translating equality downwards"

Connected through hyperedge HE-7 (induced by source paper "tally np sets and easy census functions"):
  with members:
    - "boolean operations joins and the extended low hierarchy"
    - "unambiguous computation boolean hierarchies and sparse turing complete sets"

Connected through hyperedge HE-8 (induced by source paper "translating equality downwards"):
  with members:
    - "what s up with downward collapse using the easy hard technique to link boolean and polynomial hierarchy collapses"

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.CC(Computational Complexity)