New results on multi-level aggregation
نویسندگان
چکیده
In the Multi-Level Aggregation Problem (MLAP ), requests for service arrive at nodes of an edge-weighted rooted tree T. Each is represented by a subtree X T that contains its root. This serves all are pending in X, and cost this equal to total weight X. request also incurs waiting between arrival time. The objective minimize plus subtrees. currently best online algorithms MLAP achieve competitive ratios polynomial depth, while lower bound only 3.618. paper, we report some progress towards closing gap, improving providing several tight bounds restricted variants MLAP: (1) We first study Single-Phase variant where released beginning expire unknown time θ, which provide algorithm with optimal ratio 4. (2) prove 4 on MLAP, even when path. complement matching upper deadline paths. Additionally, two results offline case: (3) can be solved optimally time, (4) give simple 2-approximation deadlines.
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 2021
ISSN: ['1879-2294', '0304-3975']
DOI: https://doi.org/10.1016/j.tcs.2021.02.016