On languages accepted by space-bounded oracle machines

Characterizations of classes of languages accepted by space-bounded oracle machines are developed. These characterizations are given in terms of the regular sets, certain information about the oracle set, and certain algebraic closure operations.This research was supported in part by the National Science Foundation under Grant MCS77-11360     

典型规则R.C框架结构在多遇水平地震作用下梁柱最佳刚度比

以典型规则框架结构为研究对象,针对框架结构在多遇水平地震作用下仍处于弹性工作阶段这一基本事实,利用结构优化设计原理及抗震设计基本理论,对框架结构提出了弹性工作阶段以顶点侧移为控制目标的结构优化模式,确定了优化目标函数,最终给出了典型规则Ｒ．Ｃ框架结构在多遇水平地震作用下下梁,柱栽面尺寸的计算公式及梁、柱最佳刚度比的表格形式。     

Gasar多孔合金规则气孔形成的糊状区长度判据

建立了规则气孔形成的糊状区长度与气泡尖端长度的理论模型,研究了合金的糊状区长度和凝固速率与Gasar多孔Cu-Cr合金的气孔结构的关系。结果表明,规则气孔形成时,糊状区长度和凝固速率均应有一适中的范围,给定凝固速率时,糊状区长度应小于气泡尖端长度。合金成分相同时,凝固速率v相似文献   

形质与情性——楷书与草书的艺术特征

文章以唐代孙过庭为研究切入点, 深入剖析了楷书与草书的形质与情性的艺术特征, 对于提升人们的书法知识和鉴赏能力具有一定的促进作用。     

关于Abel群的正则完整子半群的一个结果

研究正则完整了半群的若干性质,并由此给出Ａｂｅｌ群是特殊值的几个充要条件。     

关于群的正则子群的若干结果

提出了类似于[1][2]的正则子群及特殊子群的概念,得到了它们的若干基本性质,通过这些性质刻划了子群格的完全分配性以及给出了任意群的子群又含有限多个极小子群的条件．     

Obtaining shorter regular expressions from finite-state automata

We consider the use of state elimination to construct shorter regular expressions from finite-state automata (FAs). Although state elimination is an intuitive method for computing regular expressions from FAs, the resulting regular expressions are often very long and complicated. We examine the minimization of FAs to obtain shorter expressions first. Then, we introduce vertical chopping based on bridge states and horizontal chopping based on the structural properties of given FAs. We prove that we should not eliminate bridge states until we eliminate all non-bridge states to obtain shorter regular expressions. In addition, we suggest heuristics for state elimination that leads to shorter regular expressions based on vertical chopping and horizontal chopping.     

Efficient inclusion for a class of XML types with interleaving and counting

Inclusion between XML types is important but expensive, and is much more expensive when unordered types are considered. We prove here that inclusion for XML types with interleaving and counting can be decided in polynomial time in the presence of two important restrictions: no element appears twice in the same content model, and Kleene star is only applied to disjunctions of single elements.