The patterns of strings described by regular expression are exactly same as what can be described by finite automata. It means every formal language defined by any finite automata is also defined by a regular expression.InduJyoti
and a regular expression search algorithm invented by Ken Thompson in the mid-1960s. It also puts the theory into practice, describing a simple implementation of Thompson's algorithm. That implementation, less than 400 lines of C, is the one that went head to head with Perl above. It outpe...
Summary: We consider two formalisms for representing regular languages: constant height pushdown automata and straight line programs for regular expression... Viliam Geffert a,Carlo Mereghetti b,Beatrice Palano b - 《Information & Computation》 被引量: 58发表: 2010年 Extended Path Expressions for ...
In this work, we explore how regular expressions evolve over time, focusing on the characteristics of regular expression edits, the syntactic and semantic difference of the edits, and the feature changes of edits. Our exploration uses two datasets. First, we look at GitHub projects that have a...
Computation of Nullables : All nodes except the * nodes are not nullable. Also if some leaf node is for έ, then it is also nullable. Firstpos (Firstposition): At each node n of the syntax tree of a regular expression, we define a function firstpos(n) that gives the set of first...
formance improvements have b een obtained over other mo des of computation for several applications. This pap er describ es the use of FPGAs for fast regular expression matching. The 2.1 Regular Expressions problem is to nd all strings in input text that match the A regular expression is a ...
However, they did not give any effective method for constructing an equivalent fuzzy finite automaton from a given fuzzy regular expression. In this paper we provide such an effective method. Transforming scalars appearing in a fuzzy regular expression {alpha} into letters of the new extended ...
This article reviews the good theory: regular expressions, finite automata, and a regular expression search algorithm invented by Ken Thompson in the mid-1960s. It also puts the theory into practice, describing a simple implementation of Thompson's algorithm. That implementation, less than 400 line...
Consider an HMM as defined previously, and let r be a regular expression over the alphabet of hidden states, . We present a modified version of the forward algorithm to compute the distribution of the number of occurrences of r, which we then use in an adaptation of the Viterbi algorithm ...
The derivative is obtained by just another application of the chain rule: If we want to take gradients, we just transpose the expression and get Note that the right hand side is indeed vector in and hence, can be reshaped to a tupel of an matrix and an vector. A final remark: the...