摘要
The left-linear transformation presented by Ullman, Naughton el al. is a rule-rewriting algorithm, which is similar to the magic sets transformation. Since left-linear recursions are among the most common recursions in practice and the transformed rules can be evaluated bottom-up efficiently, the left-linear transformation has been chosen as one of the best strategies for recursive query processing by the NALL! system at Stanford and the LDL system at MCC. However, there are two strick restraints for the left-linear
基金
Project supported in part by the Grant 91028 from the Natural Science Foundation of Henan Province, China.
