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Optimization of space-saving graph search with approximate heuristic values

Jure Medvešek (2012) Optimization of space-saving graph search with approximate heuristic values. EngD thesis.

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    Finding an optimal path in a state space is often very difficult in practise. The goal of this diploma thesis is to find a space efficient algorithm which finds an optimal solution within an acceptable time frame, even in large problem spaces. Algorithm A* is relatively fast, but it has exponential space complexity. Algorithms with linear space complexity can have quadratic time complexity, in terms of A*'s time complexity. In both cases we do not check for duplicates achieved by different paths. For this type of graphs we propose an optimization of the IDA* algorithm, where we granulate the heuristic function f. The new algorithm finds an optimal solution with time complexity O(N logN), where N is the number of nodes expanded by algorithm A*. Space complexity is linear in the length of the longest expanded path. The same idea can be applied to algorithm RBFS where RBFS can be even slightly faster than IDA*.

    Item Type: Thesis (EngD thesis)
    Keywords: search, optimization, granulation
    Number of Pages: 32
    Language of Content: Slovenian
    Mentor / Comentors:
    Name and SurnameIDFunction
    akad. prof. dr. Ivan Bratko77Mentor
    Link to COBISS: http://www.cobiss.si/scripts/cobiss?command=search&base=50070&select=(ID=00009390164)
    Institution: University of Ljubljana
    Department: Faculty of Computer and Information Science
    Item ID: 1772
    Date Deposited: 13 Jul 2012 12:52
    Last Modified: 24 Sep 2012 12:00
    URI: http://eprints.fri.uni-lj.si/id/eprint/1772

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