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: "what s up with downward collapse using the easy hard technique to link boolean and polynomial hierarchy collapses"
  Abstract: During the past decade, nine papers have obtained increasingly strong consequences from the assumption that boolean or bounded-query hierarchies collapse. The final four papers of this nine-paper progression actually achieve downward collapse---that is, they show that high-level collapses induce collapses at (what beforehand were thought to be) lower complexity levels. For example, for each $k\geq 2$ it is now known that if $\psigkone=\psigktwo$ then $\ph=\sigmak$. This article surveys the history, the results, and the technique---the so-called easy-hard method---of these nine papers.

Connected through hyperedge HE-1 (induced by source paper "using the no search easy hard technique for downward collapse"):
  with members:
    - "a downward collapse within the polynomial hierarchy"

Connected through hyperedge HE-2 (induced by source paper "a moment of perfect clarity i the parallel census technique"):
  with members:
    - "a downward collapse within the polynomial hierarchy"

Connected through hyperedge HE-3 (induced by source paper "query order and the polynomial hierarchy"):
  with members:
    - "a downward collapse within the polynomial hierarchy"
    - "an introduction to query order"
    - "translating equality downwards"

Connected through hyperedge HE-4 (induced by source paper "a downward collapse within the polynomial hierarchy"):
  with members:
    - "unambiguous computation boolean hierarchies and sparse turing complete sets"
    - "translating equality downwards"

Connected through hyperedge HE-5 (induced by source paper "downward collapse from a weaker hypothesis"):
  with members:
    - "a downward collapse within the polynomial hierarchy"
    - "an introduction to query order"
    - "translating equality downwards"

Connected through hyperedge HE-6 (induced by source paper "translating equality downwards"):
  with members:
    - "a downward collapse within the polynomial hierarchy"

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)