1
vote
3answers
68 views

Draw a finite state machine which will accept the regular expression $(a^2)^* + (b^3)^*$

Draw a finite state machine which will accept the regular expression: $(a^2)^* + (b^3)^*$ In particular, I am confused by the $+$ sign, what does it exactly mean? Most literature I could find about ...
0
votes
2answers
316 views

Regular expression and DFA/NFA questions

If a language L is generated by a regular expression, then L is recognized by a DFA. I think this is true, because regular expressions describe regular languages, those of which are exactly ...
-1
votes
1answer
42 views

Finding the wrong regular expression

Which one of the following regular expressions does not define the language of all strings that ends with a. $(a + b)^*a$ $b^*aa^*(bb^*aa^*)^*$ $[a(ba)^* + b(ab)^*](a + b)^*a$ $(b + aa^*b)^*a(a + ...
0
votes
1answer
69 views

Finding regular expressions

I'm given the DFA shown below and need to find regular expressions for the following languages: $L_{1,2}^0, L_{2,1}^6, L_{2,5}^4, L_{2,3}^5, L_{1,3}^5$. The language $L_{p,q}^r$ is defined as ...
0
votes
0answers
37 views

Homework problem with expressions.

I am doing homework and I have multiple choice question that states which are the valid expressions. $bb \Phi a^*$ $(aa)^+ b(a+b)^*$ $\Phi (a+b+c)^*$ $ba^nbb: n>0$ $\lambda (a+b)^*a(bb+a)$ ...
2
votes
2answers
111 views

Basic regular expressions problem

I'm in an intro to CS theory class learning about regular expressions. I was wondering if people could give me hints as to whether I'm on the right track for these problems. I hope this particular ...
1
vote
1answer
72 views

Proving or disproving regularity of a language

The question is as follows: If L1 and L2 are not regular and L1 ⊆ L ⊆ L2, then L is regular My intuition says that it's wrong so I've been looking for a ...
0
votes
1answer
90 views

Prove min(L) = all words in L that they don't have any prefix of themselves in L

We define the minimal words language of $L, \min(L)$, to be the language of all words in $L$ that don't have any prefix in $L$. Assume $L$ is regular language. I need to prove by building an ...
0
votes
1answer
137 views

Equivalence of regular expressions

I need to prove (or disprove, but I think those are proves), that the regular expression: r = (a+b)*b(a+b)*a(a+b)* (where + is OR and * is Kleene star) is ...
0
votes
2answers
131 views

Help with regular expression subset proof

Okay, so basically I'm just showing that two ways to express a regular expression are equal, and to do so, I'm showing they're subsets of each other. The expression is: $(A^*B^*)^* \subset ...