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What is the regular expression? [closed]

Regular expression arithmeticsNegate regular expressionBasic regular expressions problemRegular expression of: $ w in Sigma^* : w text does not contain the substring 110 $.Equivalence of two regular expressionChecking some Regular Expression problemsFind regular expression for a given languageRegular expression of a languageof two letters that must alternate?Formally expressing regular expressionThree regular expressions

0

$begingroup$

Let $Sigma =1,0$.

What is the regular expression that contains at most one occurrence of substring "$11$"?

automata regular-language regular-expressions

share|cite|improve this question

edited Mar 29 at 11:38

frabala

2,5341122

asked Mar 29 at 9:51

Mahdi NaderiMahdi Naderi

1

$endgroup$

closed as off-topic by Shailesh, Paul Frost, Thomas Shelby, José Carlos Santos, Adrian Keister Mar 29 at 21:39

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Shailesh, Paul Frost, Thomas Shelby, José Carlos Santos, Adrian Keister

If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  $begingroup$
  Welcome to MSE. Your question is phrased as an isolated problem, without any further information or context. This does not match many users' quality standards, so it may attract downvotes, or be put on hold. To prevent that, please edit the question. This will help you recognise and resolve the issues. Concretely: please provide context, and include your work and thoughts on the problem. These changes can help in formulating more appropriate answers.
  $endgroup$
  – José Carlos Santos
  Mar 29 at 9:55
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  What have you tried so far?
  $endgroup$
  – frabala
  Mar 29 at 9:57
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I have tried this: 1*0*(1+11+ε)0*1* but I think it's not true!
  $endgroup$
  – Mahdi Naderi
  Mar 29 at 17:04
  

  
  
  
  

add a comment | 

0

$begingroup$

Let $Sigma =1,0$.

What is the regular expression that contains at most one occurrence of substring "$11$"?

automata regular-language regular-expressions

share|cite|improve this question

edited Mar 29 at 11:38

frabala

2,5341122

asked Mar 29 at 9:51

Mahdi NaderiMahdi Naderi

1

$endgroup$

closed as off-topic by Shailesh, Paul Frost, Thomas Shelby, José Carlos Santos, Adrian Keister Mar 29 at 21:39

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Shailesh, Paul Frost, Thomas Shelby, José Carlos Santos, Adrian Keister

If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  $begingroup$
  Welcome to MSE. Your question is phrased as an isolated problem, without any further information or context. This does not match many users' quality standards, so it may attract downvotes, or be put on hold. To prevent that, please edit the question. This will help you recognise and resolve the issues. Concretely: please provide context, and include your work and thoughts on the problem. These changes can help in formulating more appropriate answers.
  $endgroup$
  – José Carlos Santos
  Mar 29 at 9:55
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  What have you tried so far?
  $endgroup$
  – frabala
  Mar 29 at 9:57
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I have tried this: 1*0*(1+11+ε)0*1* but I think it's not true!
  $endgroup$
  – Mahdi Naderi
  Mar 29 at 17:04
  

  
  
  
  

add a comment | 

$begingroup$

Let $Sigma =1,0$.

What is the regular expression that contains at most one occurrence of substring "$11$"?

automata regular-language regular-expressions

share|cite|improve this question

edited Mar 29 at 11:38

frabala

2,5341122

asked Mar 29 at 9:51

Mahdi NaderiMahdi Naderi

1

$endgroup$

share|cite|improve this question

edited Mar 29 at 11:38

frabala

2,5341122

asked Mar 29 at 9:51

Mahdi NaderiMahdi Naderi

1

share|cite|improve this question

edited Mar 29 at 11:38

frabala

2,5341122

asked Mar 29 at 9:51

Mahdi NaderiMahdi Naderi

1

edited Mar 29 at 11:38

frabala

2,5341122

edited Mar 29 at 11:38

frabala

2,5341122

asked Mar 29 at 9:51

Mahdi NaderiMahdi Naderi

1

asked Mar 29 at 9:51

Mahdi NaderiMahdi Naderi

1

1 Answer
1

active

oldest

votes

0

$begingroup$

Regex:

^((?!11).)*(11)?(?!1)((?!11).)*$

Python:

import re

def check(s):
 if re.match(r'^((?!11).)*(11)?(?!1)((?!11).)*$', s):
 print('True')
 else:
 print('False')

check('1010101') # TRUE

check('10101101') # TRUE

check('10110101') # TRUE

check('101101011') # FALSE

check('1011101010101') # FALSE

check('1010100000101011') # TRUE

check('10101000001010111') # FALSE

check('1010100111110010101') # FALSE

share|cite|improve this answer

answered Mar 29 at 11:29

OldboyOldboy

9,30111138

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  And how do you write ^((?!11).)*(11)?(?!1)((?!11).)*$ in mathematics format?
  $endgroup$
  – Mahdi Naderi
  Mar 29 at 17:26
  

  
  
  
  

add a comment | 

0

$begingroup$

Regex:

^((?!11).)*(11)?(?!1)((?!11).)*$

Python:

import re

def check(s):
 if re.match(r'^((?!11).)*(11)?(?!1)((?!11).)*$', s):
 print('True')
 else:
 print('False')

check('1010101') # TRUE

check('10101101') # TRUE

check('10110101') # TRUE

check('101101011') # FALSE

check('1011101010101') # FALSE

check('1010100000101011') # TRUE

check('10101000001010111') # FALSE

check('1010100111110010101') # FALSE

share|cite|improve this answer

answered Mar 29 at 11:29

OldboyOldboy

9,30111138

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  And how do you write ^((?!11).)*(11)?(?!1)((?!11).)*$ in mathematics format?
  $endgroup$
  – Mahdi Naderi
  Mar 29 at 17:26
  

  
  
  
  

add a comment | 

0

$begingroup$

Regex:

^((?!11).)*(11)?(?!1)((?!11).)*$

Python:

import re

def check(s):
 if re.match(r'^((?!11).)*(11)?(?!1)((?!11).)*$', s):
 print('True')
 else:
 print('False')

check('1010101') # TRUE

check('10101101') # TRUE

check('10110101') # TRUE

check('101101011') # FALSE

check('1011101010101') # FALSE

check('1010100000101011') # TRUE

check('10101000001010111') # FALSE

check('1010100111110010101') # FALSE

share|cite|improve this answer

answered Mar 29 at 11:29

OldboyOldboy

9,30111138

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  And how do you write ^((?!11).)*(11)?(?!1)((?!11).)*$ in mathematics format?
  $endgroup$
  – Mahdi Naderi
  Mar 29 at 17:26
  

  
  
  
  

add a comment | 

$begingroup$

Regex:

^((?!11).)*(11)?(?!1)((?!11).)*$

Python:

import re

def check(s):
 if re.match(r'^((?!11).)*(11)?(?!1)((?!11).)*$', s):
 print('True')
 else:
 print('False')

check('1010101') # TRUE

check('10101101') # TRUE

check('10110101') # TRUE

check('101101011') # FALSE

check('1011101010101') # FALSE

check('1010100000101011') # TRUE

check('10101000001010111') # FALSE

check('1010100111110010101') # FALSE

share|cite|improve this answer

answered Mar 29 at 11:29

OldboyOldboy

9,30111138

$endgroup$

^((?!11).)*(11)?(?!1)((?!11).)*$

import re

def check(s):
 if re.match(r'^((?!11).)*(11)?(?!1)((?!11).)*$', s):
 print('True')
 else:
 print('False')

check('1010101') # TRUE

check('10101101') # TRUE

check('10110101') # TRUE

check('101101011') # FALSE

check('1011101010101') # FALSE

check('1010100000101011') # TRUE

check('10101000001010111') # FALSE

check('1010100111110010101') # FALSE

share|cite|improve this answer

answered Mar 29 at 11:29

OldboyOldboy

9,30111138

answered Mar 29 at 11:29

OldboyOldboy

9,30111138

answered Mar 29 at 11:29

OldboyOldboy

9,30111138