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0answers
19 views

Proof the 1 language is contained in another

Does anyone know what the best method is to prove that the intersection of Language1 and Language 2 = Language1? Where both languages are over alphabet {a,b,c}.
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1answer
272 views

induction proof for kleene star

i am going through some past exam paper questions on regular languages for some revision, and i am having a bit of trouble with converting general ideas into formal mathematical proofs. the question ...
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1answer
43 views

Expressions for $(AB)^R$, $(A \cap B)^R$, $(A \cup B)^R$

For any language A, let $A^R$ be $\{x^R \mid x \in A\}$. Then, for arbitrary languages $A$ and $B$, explicitly write down the expressions for $(AB)^R$, $(A \cap B)^R$, $(A \cup B)^R$. I am not really ...
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1answer
36 views

$L$ is a class of languages that cannot be represented by a regular expression. How to state cardinality of $L$.

$L$ is a class of languages that cannot be represented by a regular expression. The book says that the cardinality of $L$ is $2^{\aleph_0} > \aleph_0$ what's the logic behind getting the ...
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1answer
41 views

set of all reg exp vs set of all languages

$\Sigma$ = {a,b,c,d,e} V = {A,B,C,D,E,F,G,H} According to the notes: The set of all regular expressions over $\Sigma$ is infinite and countable. The set of all languages over $\Sigma$ is infinite ...
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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 ...