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arXiv 0709.1699cs.LOcs.AI
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事务处理逻辑程序的有效表列机制

Efficient Tabling Mechanisms for Transaction Logic Programs

Stony Brook University(石溪大学);University of Toronto(多伦多大学)

Paul Fodor

摘要:

在本文中,我们提出了有效的评估算法的霍恩事务逻辑(一个推广的定期霍恩逻辑程序与状态更新)。我们提出了两个互补的方法来优化事务逻辑的实现。第一种方法是基于制表和我们修改的证明理论表的状态调用和应答(实际上,相当于动态规划)。呼叫-应答表根据呼叫和进行呼叫的状态的签名进行索引。应答列包含应答统一和执行调用后状态的签名。使用基于尝试和计数的技术有效地对状态进行签名。第二种方法是基于增量评估,它适用于数据预言机包含派生关系。删除和插入(在事务oracle中执行)会更改数据库的状态。使用惯性的启发式(只有一部分状态响应于基本更新而变化),大多数时候只计算状态的变化比从头开始重新计算整个状态更便宜。这两种方法是互补的,因为第一种方法优化了在相同状态下重复调用时的评估,而第二种方法优化了在列表机制未找到调用-状态对时的新状态的评估(即第一种方法)。事务逻辑的证明理论应用了表格法和增量求值法,其模型理论是合理的、完整的。

英文摘要:

In this paper we present efficient evaluation algorithms for the Horn Transaction Logic (a generalization of the regular Horn logic programs with state updates). We present two complementary methods for optimizing the implementation of Transaction Logic. The first method is based on tabling and we modified the proof theory to table calls and answers on states (practically, equivalent to dynamic programming). The call-answer table is indexed on the call and a signature of the state in which the call was made. The answer columns contain the answer unification and a signature of the state after the call was executed. The states are signed efficiently using a technique based on tries and counting. The second method is based on incremental evaluation and it applies when the data oracle contains derived relations. The deletions and insertions (executed in the transaction oracle) change the state of the database. Using the heuristic of inertia (only a part of the state changes in response to elementary updates), most of the time it is cheaper to compute only the changes in the state than to recompute the entire state from scratch. The two methods are complementary by the fact that the first method optimizes the evaluation when a call is repeated in the same state, and the second method optimizes the evaluation of a new state when a call-state pair is not found by the tabling mechanism (i.e. the first method). The proof theory of Transaction Logic with the application of tabling and incremental evaluation is sound and complete with respect to its model theory.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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