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Added explanation of what is delta, and made some rewrites for clarity.
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Bader Abu Radi
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Every regular language hasRegular Language Has a finite indexFinite Index

For a language $L$ of finite words over an alphabet $\Sigma$, we say that two words $v,w \in \Sigma^*$ are Myhill-Nerode equivalent, denoted $v\sim w$$v\sim_L w$, if for every word $z \in \Sigma^*$, it holds that $vz \in L$ iff $wz \in L$. It is well-known that $\sim_L$ is an equivalence relation. We define $[w]_L$ to be the equivalence class of $w$ under this relation. The Then, the index of $L$ is defined as the number of equivalence classes of strings inthe relation $L$$\sim_L$.

How can I prove that every regular language has a finite index? canCan I use the Myhill-Nerode theorem?

I tried to use the fact that if $\delta^*(v) = \delta^*(w)$ then $v \sim w$$v \sim_L w$, where $\delta$ is the transition function of some DFA that recognizes $L$.

Every regular language has a finite index

For a language $L$ over an alphabet $\Sigma$, we say that two words $v,w \in \Sigma^*$ are equivalent, denoted $v\sim w$, if for every word $z \in \Sigma^*$, $vz \in L$ iff $wz \in L$. We define $[w]_L$ to be the equivalence class of $w$ under this relation. The index of $L$ is the number of equivalence classes of strings in $L$.

How can I prove that every regular language has a finite index? can I use the Myhill-Nerode theorem?

I tried to use the fact that if $\delta^*(v) = \delta^*(w)$ then $v \sim w$.

Every Regular Language Has a Finite Index

For a language $L$ of finite words over an alphabet $\Sigma$, we say that two words $v,w \in \Sigma^*$ are Myhill-Nerode equivalent, denoted $v\sim_L w$, if for every word $z \in \Sigma^*$, it holds that $vz \in L$ iff $wz \in L$. It is well-known that $\sim_L$ is an equivalence relation. We define $[w]_L$ to be the equivalence class of $w$ under this relation. Then, the index of $L$ is defined as the number of equivalence classes of the relation $\sim_L$.

How can I prove that every regular language has a finite index? Can I use the Myhill-Nerode theorem?

I tried to use the fact that if $\delta^*(v) = \delta^*(w)$ then $v \sim_L w$, where $\delta$ is the transition function of some DFA that recognizes $L$.

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reinierpost
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For a language $L$ over an alphabet $\Sigma$, we say that two words $v,w \in \Sigma^*$ are equivalent, denoted $v\sim w$, if for every word $z \in \Sigma^*$, $vz \in L$ iff $wz \in L$. We define $[w]_L$ to be the equivalence class of $w$ under this relation. The index of $L$ is the number of equivalence classclasses of strings in $L$.

How can I prove that every regular language has a finite index? can I use the Myhill-Nerode theorem?

I tried to use the fact that if $\delta^*(v) = \delta^*(w)$ then $v \sim w$.

For a language $L$ over an alphabet $\Sigma$, we say that two words $v,w \in \Sigma^*$ are equivalent, denoted $v\sim w$, if for every word $z \in \Sigma^*$, $vz \in L$ iff $wz \in L$. We define $[w]_L$ to be the equivalence class of $w$ under this relation. The index of $L$ is the number of equivalence class.

How can I prove that every regular language has a finite index? can I use the Myhill-Nerode theorem?

I tried to use the fact that if $\delta^*(v) = \delta^*(w)$ then $v \sim w$.

For a language $L$ over an alphabet $\Sigma$, we say that two words $v,w \in \Sigma^*$ are equivalent, denoted $v\sim w$, if for every word $z \in \Sigma^*$, $vz \in L$ iff $wz \in L$. We define $[w]_L$ to be the equivalence class of $w$ under this relation. The index of $L$ is the number of equivalence classes of strings in $L$.

How can I prove that every regular language has a finite index? can I use the Myhill-Nerode theorem?

I tried to use the fact that if $\delta^*(v) = \delta^*(w)$ then $v \sim w$.

added 268 characters in body; edited title
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Yuval Filmus
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how can I prove that every Every regular language has a finite index?

howFor a language $L$ over an alphabet $\Sigma$, we say that two words $v,w \in \Sigma^*$ are equivalent, denoted $v\sim w$, if for every word $z \in \Sigma^*$, $vz \in L$ iff $wz \in L$. We define $[w]_L$ to be the equivalence class of $w$ under this relation. The index of $L$ is the number of equivalence class.

How can I prove that every regular language has a finite index? can I use the Myhill-Nerode-theorem. I theorem?

I tried to use the fact that:

δ*(v) = δ*(w) => v~w enter image description here if $\delta^*(v) = \delta^*(w)$ then $v \sim w$.

how can I prove that every regular language has a finite index?

how can I prove that every regular language has a finite index? can I use the Myhill-Nerode-theorem. I tried to use the fact that:

δ*(v) = δ*(w) => v~w enter image description here

Every regular language has a finite index

For a language $L$ over an alphabet $\Sigma$, we say that two words $v,w \in \Sigma^*$ are equivalent, denoted $v\sim w$, if for every word $z \in \Sigma^*$, $vz \in L$ iff $wz \in L$. We define $[w]_L$ to be the equivalence class of $w$ under this relation. The index of $L$ is the number of equivalence class.

How can I prove that every regular language has a finite index? can I use the Myhill-Nerode theorem?

I tried to use the fact that if $\delta^*(v) = \delta^*(w)$ then $v \sim w$.

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