pumping lemma for finite regular language?
some books describe pumping lemma as this:
Let L be a regular language. Then there exists an integer p ≥ 1 depending only on L such that every string w in L of length at least p (p is called the "pumping length"[4]) can be written as w = xyz (i.e., w can be divided into three substrings), satisfying the following conditions:
- |y| ≥ 1;
- |xy| ≤ p
- for all i ≥ 0, xyiz ∈ L
Copied from Wikipedia.
However, please note that actually pumping lemma can only be used for infinite regular language.
Some people on stackoverflow also answers this problem:
"You are right - we cannot allow "pumping" words of a finite L. The thing you are missing is that the lemma says there exists a number p, but does not tell us the number.
All words longer than p can be pumped, by the lemma. For a finite L, it happens so that p is larger than the length of the longest word in L. Thus, the lemma only holds vacuously, and cannot be applied to any word in L, i.e., any word in L does not satisfy the condition of "having length at least p" as the lemma requires.
A corollary: if L has pumping length p, and there exists some word w∈L of length at least p, then L is infinite."
pumping lemma for finite regular language?的更多相关文章
- 证明与计算(7): 有限状态机(Finite State Machine)
什么是有限状态机(Finite State Machine)? 什么是确定性有限状态机(deterministic finite automaton, DFA )? 什么是非确定性有限状态机(nond ...
- 编译系统中的 NFA/DFA算法理解
1.问题概述 NFA 和 DFA浅析---要深入了解正则表达式,必须首先理解有穷自动机. 有穷自动机(Finite Automate)是用来模拟实物系统的数学模型,它包括如下五个部分: 有穷状态集St ...
- Compiler Theory(编译原理)、词法/语法/AST/中间代码优化在Webshell检测上的应用
catalog . 引论 . 构建一个编译器的相关科学 . 程序设计语言基础 . 一个简单的语法制导翻译器 . 简单表达式的翻译器(源代码示例) . 词法分析 . 生成中间代码 . 词法分析器的实现 ...
- HDU 5487 Difference of Languages
Difference of Languages Time Limit: 1000ms Memory Limit: 32768KB This problem will be judged on HDU. ...
- 4.2 Context-Free Grammars
4.2 Context-Free Grammars Grammars were introduced in Section 2.2 to systematically describe the syn ...
- Boyer-Moore algorithm
http://www-igm.univ-mlv.fr/~lecroq/string/node14.html Main features performs the comparisons from ri ...
- 软件推荐-有限元开发软件FELAC
首页:http://yuanjisuan.cn/ 有限元语言及其编译器(Finite Element Language And it’s Compiler),以下简称FELAC是中国科学院数学与系统科 ...
- CMUSphinx Learn - Basic concepts of speech
Basic concepts of speech Speech is a complex phenomenon. People rarely understand how is it produced ...
- CodeForces 1110H. Modest Substrings
题目简述:给定$1 \leq l \leq r \leq 10^{800}$,求一个长度为$n \leq 2000$的数字串$s$,其含有最多的[好]子串.一个串$s$是[好]的,如果将其看做数字时无 ...
随机推荐
- 梅特卡夫法则(Metcalfe's law)
如果一个网络中有n个人,那么网络对于每个人的价值与网络中其他人的数量成正比,于是网络对于所有人的总价值与n*(n-1)成正比.
- tableView区头不显示
不知道什么原因 如果设置tableView的样式为Group 则必须写代理 p.p1 { margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Menlo; co ...
- JQ基础语法
empty HTML 代码: <p>Hello, <span>Person</span> <a href="#">and perso ...
- 非root用户搭建hadoop伪分布式
0.安装软件列表 jdk-7u25-linux-x64.tar.gz hadoop-2.5.0.tar.gz hadoop-native-64-2.5.0.tar 1.准备Linux环境(root ...
- struts2.3 创建工程
1:在该网站下载struts2.3.16.3,目前为最新版.http://www.struts.apache.org/download.cgi 不妨下载“Full Distribution”版本 下载 ...
- Android中帧动画的创建
帧动画,实质上就是快速播放多张连接效果的图片,现在一般可用于下拉刷新时候的headView 实现步骤: 1.首先应该准备一组连接效果的图片 2.在res>drawable目录下创建xml文件,将 ...
- 自定义viewpager的界面切换动画
核心操作: 1.创建一个类实现 android.support.v4.view.ViewPager.PageTransformer 根据 position 实现判断哪个界面进行界面切换动画 publi ...
- neutron openvswitch agent实现安全组的方法
关于openstack安全组,采用一问一答的形式记录如下 1. 是加载在计算节点的还是网络节点的? 是加载在计算节点的 2. 是使用iptable规则实现的吗? M版的neutron实现了openvs ...
- js日期操作时间看板
var nowTime = null;//获取服务器时间function GetTime() { $.ajax({ url:config._domain + "/AjaxAuctionCen ...
- android 图片加载优化,避免oom问题产生
1,及时回收bitmap,在activity的onstop()和onDestory()里面调用如下代码进行bitmap的回收: // 先判断是否已经回收 if(bitmap != null & ...