巴基斯坦嘎兹-巴罗塔工程的质量管理

嘎兹-巴罗塔工程是巴基斯坦的国家重要工程,有众多世界著名的公司参加.这里介绍巴基斯坦水电咨询公司(工程师)在工程质量管理方面的一些做法.     

Exact 3-satisfiability is decidable in time O(20.16254n)

Let F = C ₁ C _m be a Boolean formula in conjunctive normal form over a set V of n propositional variables, s.t. each clause C _i contains at most three literals l over V. Solving the problem exact 3-satisfiability (X3SAT) for F means to decide whether there is a truth assignment setting exactly one literal in each clause of F to true (1). As is well known X3SAT is NP-complete [6]. By exploiting a perfect matching reduction we prove that X3SAT is deterministically decidable in time O(2^0.18674n ). Thereby we improve a result in [2,3] stating X3SAT O(2^0.2072n ) and a bound of O(2^0.200002n ) for the corresponding enumeration problem #X3SAT stated in a preprint [1]. After that by a more involved deterministic case analysis we are able to show that X3SAT O(2^0.16254n ).An extended abstract of this paper was presented at the Fifth International Symposium on the Theory and Applications of Satisfiability Testing (SAT 2002).     

《木结构工程质量验收规范》GB50206-2002内容简介

介绍《木结构工程质量验收规范》GB5 0 2 0 6 2 0 0 2的修订依据、增减内容及质量管理、质量控制、质量验收和木结构防护等方面的条文     

The mechanisms of suppression and enhancement in comprehension.

The goal of comprehension is to build coherent mental representations or structures. These structures represent clauses, sentences, paragraphs, passages, and other meaningful units. Thus, comprehending a clause requires building a mental structure to represent what that clause is about; comprehending a sentence requires building a mental structure to represent what that sentence is about; comprehending a passage requires building a mental structure to represent what that passage is about. In Gernsbacher (1990), I described a simple framework for understanding how comprehenders build mental structures during comprehension. I call this framework, the Structure Building Framework. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Efficient Algorithms to Detect and Restore Minimality, an Extension of the Regular Restriction of Resolution

A given binary resolution proof, represented as a binary tree, is said to be minimal if the resolutions cannot be reordered to generate an irregular proof. Minimality extends Tseitin"s regularity restriction and still retains completeness. A linear-time algorithm is introduced to decide whether a given proof is minimal. This algorithm can be used by a deduction system that avoids redundancy by retaining only minimal proofs and thus lessens its reliance on subsumption, a more general but more expensive technique.Any irregular binary resolution tree is made strictly smaller by an operation called Surgery, which runs in time linear in the size of the tree. After surgery the result proved by the new tree is nonstrictly more general than the original result and has fewer violations of the regular restriction. Furthermore, any nonminimal tree can be made irregular in linear time by an operation called Splay. Thus a combination of splaying and surgery efficiently reduces a nonminimal tree to a minimal one.Finally, a close correspondence between clause trees, recently introduced by the authors, and binary resolution trees is established. In that sense this work provides the first linear-time algorithms that detect minimality and perform surgery on clause trees.     

基于二阶项重写技术的逻辑自动编程理论

程序自动综合中的一个难题是:系统怎样才能自动地发现并构造出所需的子程序.本文中我们提出一种基于部分二阶逻辑的机制,称之为假说演算.我们实现了一个基于此种机制的逻辑程序自动设计的实验系统ALP.当不能由背景知识直接构造出C_i~’S时,ALP能自动导出所需子程序的输入-输出实例并综合出所需子程序.     

有效的Prolog编译实现方法

本文从实现的角度讨论了几种有效的Prolog编译技术,包括一个有效的抽象指令集、子句选择回溯,以及可插入子句的内部谓词assert a/z的实现方法.这些技术已被应用到在VAX机上开发的Prolog编译系统中.     

An algorithm to compute maximal contractions for Horn clauses

In the theory of belief revision, the computation of all maximal subsets (maximal contractions) of a formula set with respect to a set of facts is one of the key problems. In this paper, we try to solve this problem by studying the algorithm to compute all maximal contractions for Horn clauses. First, we point out and prove the conversion relationship between minimal inconsistent subsets of union of the formula set and the set of facts and maximal contractions of the formula set with respect to th...     

一个在Horn子句中求解极大缩减的算法

在信念修正理论中,一个核心问题是求解一个公式集合关于事实集合的所有极大协调子集,即极大缩减.本文尝试从算法的角度来解决这一问题,研究在Horn子句中求解所有极大缩减的算法.首先,本文指出并证明了公式集合和事实集合并集的极小不协调子集与公式集合关于事实集合的极大缩减之间的转化关系.其次,给出并证明了Horn子句集合极小不协调的一个必要条件.然后,基于上述两个结论,本文提出了一个在Horn子句中枚举公式集合和事实集合并集的极小不协调子集的交互式算法和一个通过这些极小不协调子集计算所有极大缩减的算法.最后,综合这两个算法,提出了一个在Horn子句中求解所有极大缩减的交互式算法.