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: "the grt planning system backward heuristic construction in forward state space planning"
  Abstract: This paper presents GRT, a domain-independent heuristic planning system for STRIPS worlds. GRT solves problems in two phases. In the pre-processing phase, it estimates the distance between each fact and the goals of the problem, in a backward direction. Then, in the search phase, these estimates are used in order to further estimate the distance between each intermediate state and the goals, guiding so the search process in a forward direction and on a best-first basis. The paper presents the benefits from the adoption of opposite directions between the preprocessing and the search phases, discusses some difficulties that arise in the pre-processing phase and introduces techniques to cope with them. Moreover, it presents several methods of improving the efficiency of the heuristic, by enriching the representation and by reducing the size of the problem. Finally, a method of overcoming local optimal states, based on domain axioms, is proposed. According to it, difficult problems are decomposed into easier sub-problems that have to be solved sequentially. The performance results from various domains, including those of the recent planning competitions, show that GRT is among the fastest planners.

Connected through hyperedge HE-1 (induced by source paper "where ignoring delete lists works local search topology in planning benchmarks"):
  with members:
    - "engineering benchmarks for planning the domains used in the deterministic part of ipc 4"
    - "the deterministic part of ipc 4 an overview"
    - "taming numbers and durations in the model checking integrated planning system"
    - "the metric ff planning system translating ignoring delete lists to numeric state variables"
    - "the 3rd international planning competition results and analysis"
    - "planning through stochastic local search and temporal action graphs in lpg"
    - "the ff planning system fast plan generation through heuristic search"
    - "on reasonable and forced goal orderings and their use in an agenda driven planning algorithm"

Connected through hyperedge HE-2 (induced by source paper "sapa a multi objective metric temporal planner"):
  with members:
    - "utility elicitation as a classification problem"
    - "pddl2 1 an extension to pddl for expressing temporal planning domains"
    - "vhpop versatile heuristic partial order planner"
    - "the 3rd international planning competition results and analysis"
    - "the ff planning system fast plan generation through heuristic search"
    - "efficient implementation of the plan graph in stan"

Connected through hyperedge HE-3 (induced by source paper "the metric ff planning system translating ignoring delete lists to numeric state variables"):
  with members:
    - "taming numbers and durations in the model checking integrated planning system"
    - "the 3rd international planning competition results and analysis"
    - "planning through stochastic local search and temporal action graphs in lpg"
    - "the ff planning system fast plan generation through heuristic search"
    - "on reasonable and forced goal orderings and their use in an agenda driven planning algorithm"
    - "on the compilability and expressive power of propositional planning formalisms"

Connected through hyperedge HE-4 (induced by source paper "vhpop versatile heuristic partial order planner"):
  with members:
    - "the ff planning system fast plan generation through heuristic search"
    - "flaw selection strategies for partial order planning"
    - "accelerating partial order planners some techniques for effective search control and pruning"

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.AI(Artificial Intelligence)