1.属性文法(语法制导的定义)(SyntaxDirected- Definition)。 形式:CFG的每个产生式A→对应与之相关联的一个语义规则(semantic rules)集合,每条规则形如b:=f(c1,C2,,ck),其中f是一个函数,b1C2 ck是该产生式中文法符号的属性(attributes),b有两个可能(1)是A的一 个属性,C1,C2,,Ck是产生式右部文法符号的属性或A的其它属性称b是A的 综合属性(synthesized attribute),(2)是产生式右部某个文法符号x的一个属 性,并且C12,…,C是A或产生式右部任何文法符号的属性则称b是文法符号 x的继承属性( inherited attribute) 函数f通常以表达式的形式出现

The length of a sound is the length of time during which it is held on continuously in a given word or phrase. The principal facts concerning length in English are given in the following rules: 203. Length of vowels 1. English vowels /i:/, /a: / /:/, /u:/, /a: /are longer than the other English vowels in similar context, i.e., when surrounded by the same sounds, and pronounced with the same degree of stress. Thus

4.3.2线性映射的运算的定义与性质 定义线性映射的运算(加法与数域K上的数量乘法) 设f:U→V,g:U→V为线性映射,定义f+g为 f+g:U→V, af(a)+g(a)(a∈U) 定义kf(Vk∈K)为 kf:u→v akf(a)(a∈U) 说明f+g与kf仍为线性映射。 命题Hom(U,V)在加法和数乘下构成数域K上的线性空间。 证明逐项验证

一、基本概念 1.数集的相关概念: (1)邻域:设a∈R,δ>0。满足绝对值不等式|x-a<的全体实数x的集合称为点a的δ邻域,记作U(a,),或简单地记为U(a)

6.1线性空间的定义与性质 定义1设V是一个非空集合,R为实数域,如果对任 意两个元素a,∈,总有唯一的一个元素γ∈V与 之对应,称为a,B的和,记作y=a+B;对于任一 个数k∈R与任一个元素a∈V,总有唯一的一个元 素δ∈V与之对应,称为k与a的积,记为δ=ka; 两种运算满足以下八条运算规律

Multiple Choice If one person can perform a task in fewer hours than another, you know the person has in performing the task. a. an absolute advantage. b. a comparative advantage. C. both a comparative advantage and an absolute advantage. rd. neither an absolute nor a comparativ advantage

2002-2003学年第二学期概率论与数理统计(B)期末考试试卷答案 一.(本题满分35分,共有5道小题,每道小题7分) 1.设A、B、C是三个随机事件,且P(A)=PB)=P(C)=,p(b)=,P(C)= P(AC)=0.试求A、B、C这三个随机事件中至少有一个发生的概率. 解: 所求概率为P(A∪BC).由概率的加法公式得 (AUBUC)=P(A)+P(B)+P(C)-P(AB)-P(BC)-P(AC)+P(ABC). 由于 ABC AC,由概率的单调性、非负性及题设中的条件,得0≤P(ABC)P(AC)

定理3.4.1若AcR\,BcR”,且均可测,则A×B={(a,b)|a∈A,b∈B} R\×R为可测集,且m(A×B)= mAXmB 证明1)若区间IcR\,I2cR,则显然I×I2为R\×R中的区间,从 而可测。且|I×12|=|I|×|I2|

材料工程基础试卷B答案 一、选择题(共15题,每题2分,共30分) .A 2. 3.A 4.C 5.B 6B7B8C9.A10.C 11C12.A13.B14.A15.B

The location of the dehydration factory must be considered very carefully, because, whereas at one time proximity to the source of raw materials was of paramount importance, availability of an adequate labour force and the provision for effluent disposal will, perhaps, constitute a more pressing requirement. A rural environment is obviously better than a location in a highly industrialised area, because the operation involves the utilisation of a considerable amount