1 L can be represented by a regexp L is a regular language ⇐ 2
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13 fév 2015 · 1 Q: Let Σ = 1a, bl Write a regular expression for the set of all strings in c 1W : every odd position in W is 1l 0, 1 1 0 0, 1 3 Q: For the NFA
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4 déc 2015 · 1 DFAs: Design a DFA for each of the following languages (all over the (a) (5 points) {w every odd position of w is a 0} (the first position is always Subset Construction: Consider the regular expression (ab + aba)∗
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Part i –{w every odd position is 1} This is similar guage, we prove that L is regular by constructing a DFA which recognises the reverse of L, in which the least
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Theorem: The reverse of a regular language is also a regular { w every odd position in w is a 1 } (1(0 + Given any regexp R, we will construct an NFA N s t
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{ww begins with a 1 and ends with a 0} b {w every odd position of w is a 1} Now generate regular expressions based on the previous DFAs in Question 2
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16 fév 2004 · (b) {w G {0 , 1 }* ² every odd position of w is a 1 } (Note that ifw /= e, the first of an NFA from a regular expression, which gives an NFA with
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CHAPTER 1 / REGULAR LANGUAGES {w every odd position of w is a 1} j {w/ w regular expression that generates D (Suggestion: Describe D more simply )
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Let L be a regular language with
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Feb 13 2015 1. Q: Let ? = 1a
Dec 4 2015 1. DFAs: Design a DFA for each of the following languages (all over the ... (a) (5 points) {w
Mar 18 2002 {ww starts with 0 and has odd length
1. Give NFAs with the specified number of states recognizing each of the (b) Prove that L has a regular expression where L is the set of strings ...
A Suppose some regular expression of length ????can be converted an NFA for some ?????? B Suppose each regular expression of length ????can be converted an NFA for some ?????? C Suppose each regular expression of length at most k can be converted an NFA for some ?????? D None of the above
{ w w = ? or every odd position in w is a 1 } Transform a DFA for L into a regular expression by removing states and re-labeling the arcs with regular expressions
2 (Sipser problem 1 31) For any string w = w 1w 2 ···w n the reverse of w written as wR is the string w in reverse order w n ···w 2w 1 For any language A let AR = {wR w ? A} Show that if A is regular so is AR [20 points] Solution: One solution is recursively (or inductively) de?ne a reversing operation on regular
{q n+1} if q ?F and c =w n+1 q 0?=q 0 F ?={q n+1} We propose that M ? recognizes L ? Since the first part of ?? follows the same path that w would take through L we know that reading w will terminate at some state q ?F Q? added a single state that is only reachable from the states in F on character w n+1 If there are any
1 0 0 0 1 0;1 c The language fW: W contains an odd number of 1’s or exactly two 0’sg The NFA must have six states: 1 1 0 0 0 0 1 1 " " 1 6 Q: Give regular expressions describing the following languages in which the alphabet is f0;1g: A: a fW: W has length at least 3 and its second symbol is 1g: 1 b fW: Every odd position of W is a 0g
•Lemma (1 55): If L is described by a regular expression R then there exists an NFA that accepts it Proof: For each type of regular expression develop an NFA that accepts it R= a a ?? R= R 1 ?R 2 R 1 R 2 are regular R= ? R= R 1 R 2 R 1 R 2 are regular R=Ø R= R 1 * R 1 is regular CS 310 –Fall 2016 Pacific University Proof
Is the expression 00 a regular expression?
Yes the above one is a Regular Expression containing language Set as follows : Language L1 = {00, … View the full answer Transcribed image text: Does the expression ( (0 + 1) (0 + 1)*)* 00 (0 + 1)* denote the language in Example 3.5 (both editions)? Briefly explain.
What is the operator precedence of a regular expression?
?If Ris a regular expression, R*is a regular expression for the Kleene closureof R. ?If Ris a regular expression, (R)is a regular expression with the same meaning as R. Operator Precedence ?Regular expression operator precedence is (R) R* R 1 R 2 R 1 | R 2 ?So ab*c|dis parsed as ((a(b*))c)|d Regular Expressions, Formally
What regular expressions match even or odd numbers?
Useful regular expressions that will match even or odd numbers such as zip code, state id, or passport number. Regular Expression To Match Even Or Odd Numbers - Regex Pattern Useful regular expressions that will match even or odd numbers such as zip code, state id, or passport number. Skip to content Regex Pattern Menu Menu Home Dates & Times URI
What is a regular expression for a string containing alternate 0'S and 1's?
Now, a regular expression for set of all strings consisting of alternate 0’s and 1’s would be (01)*, where it can accept ?, 01, 0101, 010101…..etc but this restricts the string as it can always begin with 0 only. Again, the expression (10)* will accept ?, 10, 1010, 101010….etc but this too restricts string as it can always begin with 1 only.
FORMAL LANGUAGES AUTOMATA AND COMPUTABILITY