First it is shown that for any rooted tree T with n vertices, and parameter m G n, there is a ''shortcutting'' set S of at most m arcs from the transitive closure Ž . T\* of T such for any ¨, w g T \*, there is a dipath in T j S from ¨to w of length Ž Ž .. Ž O ␣ m, n . An equivalent result has been
Parallel Implementation of Tree Skeletons
✍ Scribed by D.B. Skillicorn
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 277 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0743-7315
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✦ Synopsis
Trees are a useful data type, but they are not routinely included in parallel programming systems, in part because their irregular structure makes partitioning and scheduling difficult. We present a method for algebraically constructing implementations of tree skeletons, high-level homomorphic operations that execute in parallel. Many computations on binary trees can be performed in O(log n) parallel time using n processors, even taking account of communication costs. We extend these results to trees with arbitrary and variable degree. Then we show that it is possible to implement a distributed version of homomorphisms on binary trees, taking O(n/p ؉ log 2 p) parallel time on p Ͻ n processors, for trees of any skew and taking full account of communication costs. Under slightly stronger restrictions on the underlying functions, this can be improved to O(n/p ؉ log p). Furthermore, the technique for deriving distributed versions is algebraic, allowing the automatic generation of code for SPMD and data-parallel architectures.
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