Consider the set of all strings consisting of one or more “a”s. Explain the flaw in this grammar and if possible, give an example string this grammar produces that is not in the set:
<S>* ::= <T> | a <T> ::= a <T> | <empty>
language is SML/NJ
<S>* ::= <T> | a <T> ::= a <T> | <empty> This grammar does not always produce strings with one or more a's this below generates an empty string. <S> -> <T> -> <empty> This is the flaw in this grammar.
Consider the set of all strings consisting of one or more “a”s. Explain the flaw in...
2. 9 marks] Strings. Consider the following definitions on strings Let U be the set of all strings Let s be a string. The length or size of a string, denoted Is, is the number of characters in s Let s be a string, and i e N such that 0 < ί < sl. We write s[i] to represent the character of s at index i, where indexing starts at 0 (so s 0] is the first character, and...
2. 9 marks] Strings. Consider the following definitions on strings Let U be the set of all strings. Let s be a string. The length or size of a string, denoted Is, is the number of characters in s Let s be a string, and ie N such that 0 Si< Is. We write si] to represent the character of s at index i, where indexing starts at 0 (so s(0 is the first character, and s|s -1 is the...
13.) Write a grammar for the language consisting of strings that have n copies of the letter a followed by one more number of copies of the letter b, where n>0. For example, the strings abb, aaaabbbbb, and aaaaaaaabbbbbbbbb are in the language but a, ab, ba, and aaabb are not. Answer the aaaaaabbbbbbbh are in the languagebr 14.) Draw parse trees for the sentences abb and aabbb, as derived from the grammar of Problem 13. Answer:
Write down the regular expressions for the following set of strings over {a, b}: 1.Strings that contain no more than one occurrence of the string aa. 2.All strings containing aba: 3.All strings of odd length 4.A string in this language must have at least two a's. 5.All strings that begin with a, and have an even number of b Bonus - All strings with “a” at every odd position
Construct context-free grammars that generate the given set of
strings. If the grammar has more than one variable, we will ask to
write a sentence describing what sets of strings expect each
variable in the grammar to generate. For example, if the grammar
was:
I could say "C generates binary strings of length one, E
generates (non-empty) even length binary strings, and O generates
odd length binary strings." It is also fine to use a regular
expression, rather than English,...
Construct context-free grammars that generate the given set of
strings. If the grammar has more than one variable, we will ask to
write a sentence describing what sets of strings expect each
variable in the grammar to generate. For example, if the grammar
was:
I could say "C generates binary strings of length one, E
generates (non-empty) even length binary strings, and O generates
odd length binary strings." It is also fine to use a regular
expression, rather than English,...
For each of the following, construct context-free grammars that generate the given set of strings. If your grammar has more than one variable, we will ask you to write a sentence describing what sets of strings you expect each variable in your grammar to generate. For example, if your grammar were: S → EO E → EE CC 0+ EC C+01 We would expect you to say “E generates (non-empty) even length binary strings; O generates odd length binary strings;...
Design a non-ambiguous grammar generating the language consisting of all binary strings, which contain an odd number of 0’s and an odd number of 1’s. Justify correctness of your construction.
1. Use a Regular Expression to define the set of all bit strings
of one or more 0's followed by only a 1.
2. Use a Regular Expression to define the set of all bit string
of two or more symbols followed by three or more 0's.
3. Are these two grammars the same?
a. S-> aSb|ab|λ
b. S-> aAb|ab A->aAb|λ
4. Use the process of elimination to find the language of the
following FA: (see picture for diagram)
5....
DO NUMBER 4 AND 5
2. Let {acgt} and let L be the language of strings consisting of repeated copies of the pairs at, ta, cg, gc. Construct both a DFSM to accept the language and a regular expression that represents the language 3. Let a,b. For a string w E X", let W denote the string w with the a's and b's flipped. For example, for w aabbab: w bbaaba wR babbaa abaabb {wwR Construct a PDA to accept...