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: "backdoors to acyclic sat"
  Abstract: Backdoor sets, a notion introduced by Williams et al. in 2003, are certain sets of key variables of a CNF formula F that make it easy to solve the formula; by assigning truth values to the variables in a backdoor set, the formula gets reduced to one or several polynomial-time solvable formulas. More specifically, a weak backdoor set of F is a set X of variables such that there exits a truth assignment t to X that reduces F to a satisfiable formula F[t] that belongs to a polynomial-time decidable base class C. A strong backdoor set is a set X of variables such that for all assignments t to X, the reduced formula F[t] belongs to C. #R##N#We study the problem of finding backdoor sets of size at most k with respect to the base class of CNF formulas with acyclic incidence graphs, taking k as the parameter. We show that #R##N#1. the detection of weak backdoor sets is W[2]-hard in general but fixed-parameter tractable for r-CNF formulas, for any fixed r>=3, and #R##N#2. the detection of strong backdoor sets is fixed-parameter approximable. #R##N#Result 1 is the the first positive one for a base class that does not have a characterization with obstructions of bounded size. Result 2 is the first positive one for a base class for which strong backdoor sets are more powerful than deletion backdoor sets. #R##N#Not only SAT, but also #SAT can be solved in polynomial time for CNF formulas with acyclic incidence graphs. Hence Result 2 establishes a new structural parameter that makes #SAT fixed-parameter tractable and that is incomparable with known parameters such as treewidth and clique-width. #R##N#We obtain the algorithms by a combination of an algorithmic version of the Erd\"os-P\'osa Theorem, Courcelle's model checking for monadic second order logic, and new combinatorial results on how disjoint cycles can interact with the backdoor set.

Connected through hyperedge HE-1 (induced by source paper "complexity and approximability of parameterized max csps"):
  with members:
    - "solving maxsat and sat on structured cnf formulas"
    - "tractable answer set programming with weight constraints bounded treewidth is not enough"
    - "guarantees and limits of preprocessing in constraint satisfaction and reasoning"
    - "model counting for formulas of bounded clique width"
    - "a characterization of approximation resistance for even k partite csps"
    - "satisfiability of acyclic and almost acyclic cnf formulas"
    - "majority is stablest discrete and sos"
    - "not so easy problems for tree decomposable graphs"

Connected through hyperedge HE-2 (induced by source paper "backdoors to abduction"):
  with members:
    - "backdoors to normality for disjunctive logic programs"
    - "backdoors to satisfaction"
    - "backdoors to tractable answer set programming"

Connected through hyperedge HE-3 (induced by source paper "upper and lower bounds for weak backdoor set detection"):
  with members:
    - "backdoors to satisfaction"

Connected through hyperedge HE-4 (induced by source paper "strong backdoors to bounded treewidth sat"):
  with members:
    - "linear kernels and single exponential algorithms via protrusion decompositions"
    - "strong backdoors to nested satisfiability"
    - "backdoors to satisfaction"
    - "finding topological subgraphs is fixed parameter tractable"
    - "almost 2 sat is fixed parameter tractable"
    - "cutset sampling for bayesian networks"

Connected through hyperedge HE-5 (induced by source paper "strong backdoors to nested satisfiability"):
  with members:
    - "strong backdoors to bounded treewidth sat"
    - "backdoors to satisfaction"
    - "almost 2 sat is fixed parameter tractable"
    - "obtaining a planar graph by vertex deletion"

Connected through hyperedge HE-6 (induced by source paper "backdoors to tractable answer set programming"):
  with members:
    - "guarantees and limits of preprocessing in constraint satisfaction and reasoning"
    - "the parameterized complexity of reasoning problems beyond np"
    - "backdoors to normality for disjunctive logic programs"
    - "numvc an efficient local search algorithm for minimum vertex cover"
    - "backdoors to abduction"
    - "the good the bad and the odd cycles in answer set programs"
    - "strong backdoors to bounded treewidth sat"
    - "strong backdoors to nested satisfiability"

Connected through hyperedge HE-7 (induced by source paper "backdoors to satisfaction"):
  with members:
    - "the good the bad and the odd cycles in answer set programs"
    - "strong backdoors to bounded treewidth sat"
    - "strong backdoors to nested satisfiability"
    - "augmenting tractable fragments of abstract argumentation"
    - "3 sat faster and simpler unique sat bounds for ppsz hold in general"
    - "backdoors to tractable answer set programming"
    - "limits of preprocessing"
    - "subset feedback vertex set is fixed parameter tractable"

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.DS(Data Structures and Algorithms)