Let S = k x 1 x n be the polynomial ring in n variables over a field k, let M be a graded S-module, and let be a minimal free resolution of M over S. As usual, we define the associated (graded) Betti numbers Ξ² i j = Ξ² i j M by the formula \* The first and third authors are grateful to the NSF for
Decision Tree Complexity and Betti Numbers
β Scribed by Andrew Chi-Chih Yao
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 381 KB
- Volume
- 55
- Category
- Article
- ISSN
- 0022-0000
No coin nor oath required. For personal study only.
β¦ Synopsis
We show that any algebraic computation tree or any fixed-degree algebraic tree for solving the membership question of a compact set S R n must have height greater than 0(log(; i (S)))&cn for each i, where ; i (S) is the ith Betti number. This generalizes a well-known result by Ben-Or who proved this lower bound for the case i=0, and a recent result by Bjo rner and Lova sz who proved this lower bound for all i for linear decision trees. ] 1997 Academic Press Recently, Bjo rner and Lova sz [BL92] made another step towards linking ; i with computational complexity, showing that for linear decision trees 0(log ; i (S)) is a lower bound for all i 0; more precisely, they showed C 1 (S) log 3 ( i 0 ; i (S)).
In this paper, we extend [BL92] to general algebraic trees, thus giving a fairly complete answer to the question raised in [Be83] concerning the link between algebraic decision tree complexity and higher Betti numbers. We proved that, for any compact set S R n , C d (S), C(S) 0(log( i 0 ; i (S)))&cn (for all fixed d ). We also apply this article no.
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