上下文无关文法（Context-Free Grammar, CFG）是一个4元组G=(V, T, S, P)，其中，V和T是不相交的有限集，S∈V，P是一组有限的产生式规则集，形如A→α，其中A∈V，且α∈(V∪T)*。V的元素称为非终结符，T的元素称为终结符，S是一个特殊的非终结符，称为文法开始符。 设G=(V, T, S, P)是一个CFG，则G产生的语言是所有可由G产生的字符串组成的集合，即L(G)={x∈T* | Sx}。一个语言L是上下文无关语言（Context-Free Language, CFL），当且仅当存在一个CFG G，使得L=L(G)。 *⇒ 例如，设文法G：S→AB A→aA|a B→bB|b 则L(G)={a^nb^m | n,m>=1} 其中非终结符都是大写字母，开始符都是S，终结符都是小写字母。
标签： Context-Free Grammar CFG
上传时间： 2013-12-10
上传用户：gaojiao1999
SVMcfg: Learns a weighted context free grammar from examples. Training examples (e.g. for natural language parsing) specify the sentence along with the correct parse tree. The goal is to predict the parse tree of new sentences.
标签： examples e.g. weighted Training
上传时间： 2014-07-26
上传用户：zsjzc
Draak is a multi-language, macro compiler, meaning all syntax and code generation is defined in a single file. Draak is a single binary that is able to compile any context free language (like C, Pascal, Java) for any platform with only 1 file. Draak Compiler是一个多语言，宏编译器，可以在一个单独的文件中定义所有的语法和代码生成。Draak 是一个单独的二进制文件，可以在任意平台上只使用一个文件来编译任何上下文无关的语言（类似 C, Pascal, Java）。
标签： multi-language generation compiler defined
上传时间： 2013-12-30
上传用户：a673761058
Computer science as an academic discipline began in the 1960’s. Emphasis was on programming languages, compilers, operating systems, and the mathematical theory that supported these areas. Courses in theoretical computer science covered finite automata, regular expressions, Context-Free languages, and computability. In the 1970’s, the study of algorithms was added as an important component of theory. The emphasis was on making computers useful. Today, a fundamental change is taking place and the focus is more on a wealth of applications. There are many reasons for this change. The merging of computing and communications has played an important role. The enhanced ability to observe, collect, and store data in the natural sciences, in commerce, and in other fields calls for a change in our understanding of data and how to handle it in the modern setting. The emergence of the web and social networks as central aspects of daily life presents both opportunities and challenges for theory.
标签： Foundations Science Data of
上传时间： 2020-06-10
上传用户：shancjb
free BSD
上传时间： 2013-12-11
上传用户：731140412
中文译名《最优C/C++编程秘诀》。书中对new/delete、malloc/free，构造/析构函数等等C/C++难点问题有详细深入的讲解。
上传时间： 2013-12-31
上传用户：dongbaobao
一个FREE编译器原码，用于学习LEX和YA
上传时间： 2014-01-17
上传用户：netwolf
FREE embed os FOR ARM ,51等多种MCU
上传时间： 2015-01-28
上传用户：chenbhdt
Java Clock is a FREE Java applet used to display a clock on your Web pages. You can display either analog or digital clock. The full source code of this applet is also available (visit my home page to download it). You may use this applet on your Web pages WITHOUT paying me fee or royalty as long as credit is given (a link to my home page is enough).
标签： display Java applet either
上传时间： 2014-01-12
上传用户：woshiayin
free software based on toyFDTD
标签： software toyFDTD based free
上传时间： 2015-02-16
上传用户：talenthn
