context-free-grammar

For a context-free grammar G over Σ = {0, 1, 2}, with start variable S: S → 0S0 | 1S1 | 2S2 | Y Y → 22 How do i turn this into an equivalent Push-Down automaton A pushdown automaton can push symbols on top of a stack and pop them off. It can also base its transitions on the topmost stack symbol. We need to think of a mechanism that will allow us accept the right language by manipulating our stack. The language your grammar generates has the following characteristics: It has 22 in the middle It is a palindrome over {0, 1, 2} . That is, it reads the same forwards as backwards. We need to

I am currently writing a csv parser. The definition of csv format is given by RFC4180 which is defined by ABNF. So the definition of csv is absolutely a contex-free grammar. However, I would like to know if csv is regular grammar? So that I could parse it with just a finite state machine. Furthermore, if it is exactly a regular grammar and can be parsed by finite state machine, does that mean it can be also parsed by regular expression? I don't have any formal theory available to verify this, but I'm pretty sure CSV files can reliably be parsed with regular expressions. It's probably best to

I'm trying to eliminate left recursion from the following extract of a grammar - expression := fragment ( ( + | - | * | / ) fragment )* fragment := identifier | number | ( + | - ) fragment | expression The issue is that expression can go to fragment, can go to expression. I've tried a bunch of ways to eliminate it, some look like they work (in JavaCC) but I'm a)unsure of their correctness, and b) pretty sure I've broken associativity by changing the structure of the grammar. I'm pretty sure I need an expression', and have fragment := identifier | number | ( + | - ) fragment | expression

After having read for the zillionth time a question about "How do I parse HTML with Regex" on Stackoverflow, I got myself interested again in grammars, grabbed my university scripts and after a few minutes I wondered how I've ever passed my exams. As a simple (well, "simple" I expected it to be) exercise I tried to write a CFG that produces valid python tuples (for simplicity's sake only using the identifiers a , b and c ). After some good time I now came up with this: G = ( {Tuple, TupleItem, Id}, {“a”, “b”, “c”, “,”, “(“, “)”}, P, Tuple) Being P: Tuple → “(“ TupleItem “)” Tuple → “(“

Have found C++ BNF and there next lines selection-statement: if ( condition ) statement if ( condition ) statement else statement Now trying to write parser. Need to build parse tree. On input i have BNF and source file. But i'm stucked in how i can point my parser what if condition evaluated to true, then it need to execute first statement otherwise else block? Thanks. Conditional statements have a simple recursive structure. The corresponding recursive descent parser has a similarly simple recursive structure. Abstractly, the interior conditionals are parsed as follows: <cond> -> if

How can I construct a context free grammar for the following language: L = {a^l b^m c^n d^p | l+n==m+p; l,m,n,p >=1} I started by attempting: S -> abcd | aAbBcd | abcCdD | aAbcdD | AabBcCd and then A = something else... but I couldn't get this working. . I was wondering how can we remember how many c's shud be increased for the no. of b's increased? For example: string : abbccd The grammar is : S1 -> a S1 d | S2 S2 -> S3 S4 S3 -> a S3 b | epsilon S4 -> S5 S6 S5 -> b S5 c | epsilon S6 -> c S6 d | epsilon Rule 1 adds equal number of a's and d's. Rule 3 adds equal number of a's and b's. Rule 5

I am trying to develop a Voice based application that would accept user input as speech and perform some actions based on the input. This is my first ever venture into this technology and I am learning while developing it. I am using Microsoft SAPI shipped with dotnet 4 to recognize speech. So far, I have learned about the two types of modes it supports. Speech recognition (SR) has two modes of operation: Dictation mode — an unconstrained, free-form speech interpretation mode that uses a built-in grammar provided by the recognizer for a specific language. This is the default recognizer.

I have the following grammar for expressions involving binary operators (| ^ & << >> + - * /): expression : expression BITWISE_OR xor_expression | xor_expression xor_expression : xor_expression BITWISE_XOR and_expression | and_expression and_expression : and_expression BITWISE_AND shift_expression | shift_expression shift_expression : shift_expression LEFT_SHIFT arith_expression | shift_expression RIGHT_SHIFT arith_expression | arith_expression arith_expression : arith_expression PLUS term | arith_expression MINUS term | term term : term TIMES factor | term DIVIDE factor | factor factor :