### Abstract

We observe a repeated-update problem in the process of updating walkabout strengths of the DeltaBlue algorithm, which is known as a fast constraint solving method based on local propagation. According to the basic references on the DeltaBlue algorithm, the time complexity of the planning phase is described as O(MN) for a constraint problem such that the number of constraints is N and the maximum number of methods a constraint has is M. We, however, point out that the time complexity is not O(MN) using a very simple example. In this example, the time complexity is exponential order for N. Then we present a corrected DeltaBlue algorithm whose time complexity is O(EN^{2}) for a constraint problem such that the number of constraints is N and the maximum number of variables a constraint has is E. Finally we measure the performance of the corrected DeltaBlue algorithm using two benchmarks.

Original language | English |
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Pages (from-to) | 331-341 |

Number of pages | 11 |

Journal | Constraints |

Volume | 3 |

Issue number | 4 |

DOIs | |

Publication status | Published - 1998 Oct 1 |

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### Keywords

- Constraint solving algorithm
- DeltaBlue algorithm
- Local propagation

### ASJC Scopus subject areas

- Software
- Discrete Mathematics and Combinatorics
- Computational Theory and Mathematics
- Artificial Intelligence

### Cite this

*Constraints*,

*3*(4), 331-341. https://doi.org/10.1023/A:1009776022504