John Doe claims that the language L, of all strings over the alphabet Σ = { a, b } that contain an even number of occurrences of the letter ‘a’, is not a regular language. He offers the following “pumping lemma proof”. Explain what is wrong with the “proof” given below. “Pumping Lemma Proof” We assume that L is regular. Then, according to the pumping lemma, every long string in L (of length m or more) must be “pumpable”. We...
Use the pumping lemma to show that the following language is non-regular: [a"b2n,n> 1) 1) usually we need to find a word in the language as an example, what length of the word we should use as the example? what are the three possible ways to choose substring y in the pumping lemma? if a language satisfy the pumping lemma, is this language a regular language? Why?
Let S = {a, b}. Show that the language L = {w EX : na(w)<n(w) } is not regular.
(d) Let L be any regular language. Use the Pumping Lemma to show that In > 1 such that for all w E L such that|> n, there is another string ve L such that lvl <n. (4 marks) (e) Let L be a regular language over {0,1}. Show how we can use the previous result to show that in order to determine whether or not L is empty, we need only test at most 2" – 1 strings. (2...
Let L be a regular language on sigma = {a, b, d, e}. Let L' be the set of strings in L that contain the substring aab. Show that L' is a regular language.
Let Σ {0, 1, 2} Use the Pumping Lemma to show that the language L defined below is not regular L-(w: w Σ*, w is a palindrome} Note that a palindrome is a word, number, or other sequence of characters which reads the same backward as forward, such as mom or eye.
5. Consider the language L = {1'0/1k e {0,1}* |i >01) >0 Ak = i*j}; to show that Lis! not a regular language using pumping lemma, the correct choice for the word is: a. 10011 x=1- b. 1POP 1P Z=1 Le 1290? 12p* Z=1P OPS 2P Y-101 YEK d. 10P1P y=1" t:P
4. (Non-CFLs) Prove that the following languages are not context-free. (b) The following language over the alphabet {a, b, c}: B = {aix | i ≥ 0, x ∈ {b, c}* , and if i = 1 then x = ww for some string w}. (Careful: B satisfies the pumping lemma for CFLs! Make sure you understand why, but you don’t need to write it down.)
1. Construct a DFSM to accept the language: L w E ab): w contains at least 3 as and no more than 3 bs) 2. Let E (acgt and let L be the language of strings consisting of repeated copies of the pairs at, ta, cg. ge. Construct both a DFSM to accept the language and a regular expression that represents the language. 3. Let ab. For a string w E , let w denote the string w with the...
1. Construct a DFSM to accept the language: L = {w € {a,b}*: w contains at least 3 a's and no more than 3 b's} 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 ', let W denote the string w with the...