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The following notation $| L_1L_2 |$ = $| L_1 |$ $| L_2 |$ denotes that the number of strings in the $L_1L_2$ concatenation is the same as the product of two numbers $| L_1 |$ and $| L_2 |$. If this statement is always true for any two languages, give formal arguments for proof it and if not, you need to show two languages $​​L_1$ and $L_2$ such that $| L_1L_2 |$ is not equal to$| L_1 |$ $| L_2 |$.

I tried to solve this by induction proof, but i don't see what is the step base , i'm confuse about what step base .I think in the proof is something like:

$\epsilon$ = void string

L1 = {$\epsilon$} then proof $|\{\epsilon\} L2 |$ = $|\{\epsilon\}|$ $| L_2 |$.

By definition, $\{\epsilon\} L_2 $ = $L_2$, so this is $|\{\epsilon\} L2 |$ = $|L_2|$

Now,it's easy to see |{$\epsilon$}| = 1 therefore $|\{\epsilon\}|$ $| L_2 |$ = 1 $|L_2|$ = $|L_2|$

Well, I don't know if I'm right, but if so, then how can I proceed with the inductive step. Thanks for the help.

The following notation $| L_1L_2 |$ = $| L_1 |$ $| L_2 |$ denotes that the number of strings in the $L_1L_2$ concatenation is the same as the product of two numbers $| L_1 |$ and $| L_2 |$. If this statement is always true for any two languages, give formal arguments for proof it and if not, you need to show two languages $​​L_1$ and $L_2$ such that $| L_1L_2 |$ is not equal to$| L_1 |$ $| L_2 |$.

I tried to solve this by induction proof, but i don't see what is the step base , i'm confuse about what step base .I think in the proof is something like:

L1 = {$\epsilon$} then proof $|\{\epsilon\} L2 |$ = $|\{\epsilon\}|$ $| L_2 |$.

By definition, $\{\epsilon\} L_2 $ = $L_2$, so this is $|\{\epsilon\} L2 |$ = $|L_2|$

Now,it's easy to see |{$\epsilon$}| = 1 therefore $|\{\epsilon\}|$ $| L_2 |$ = 1 $|L_2|$ = $|L_2|$

Well, I don't know if I'm right, but if so, then how can I proceed with the inductive step. Thanks for the help.

The following notation $| L_1L_2 |$ = $| L_1 |$ $| L_2 |$ denotes that the number of strings in the $L_1L_2$ concatenation is the same as the product of two numbers $| L_1 |$ and $| L_2 |$. If this statement is always true for any two languages, give formal arguments for proof it and if not, you need to show two languages $​​L_1$ and $L_2$ such that $| L_1L_2 |$ is not equal to$| L_1 |$ $| L_2 |$.

I tried to solve this by induction proof, but i don't see what is the step base , i'm confuse about what step base .I think in the proof is something like:

$\epsilon$ = void string

L1 = {$\epsilon$} then proof $|\{\epsilon\} L2 |$ = $|\{\epsilon\}|$ $| L_2 |$.

By definition, $\{\epsilon\} L_2 $ = $L_2$, so this is $|\{\epsilon\} L2 |$ = $|L_2|$

Now,it's easy to see |{$\epsilon$}| = 1 therefore $|\{\epsilon\}|$ $| L_2 |$ = 1 $|L_2|$ = $|L_2|$

Well, I don't know if I'm right, but if so, then how can I proceed with the inductive step. Thanks for the help.

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How do i start this inductive proof on Languages? $| L_1L_2 |$ = $| L_1 |$ $| L_2 |$

The following notation $| L_1L_2 |$ = $| L_1 |$ $| L_2 |$ denotes that the number of strings in the $L_1L_2$ concatenation is the same as the product of two numbers $| L_1 |$ and $| L_2 |$. If this statement is always true for any two languages, give formal arguments for proof it and if not, you need to show two languages $​​L_1$ and $L_2$ such that $| L_1L_2 |$ is not equal to$| L_1 |$ $| L_2 |$.

I tried to solve this by induction proof, but i don't see what is the step base , i'm confuse about what step base .I think in the proof is something like:

L1 = {$\epsilon$} then proof $|\{\epsilon\} L2 |$ = $|\{\epsilon\}|$ $| L_2 |$.

By definition, $\{\epsilon\} L_2 $ = $L_2$, so this is $|\{\epsilon\} L2 |$ = $|L_2|$

Now,it's easy to see |{$\epsilon$}| = 1 therefore $|\{\epsilon\}|$ $| L_2 |$ = 1 $|L_2|$ = $|L_2|$

Well, I don't know if I'm right, but if so, then how can I proceed with the inductive step. Thanks for the help.

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