prove or disprove if the following language is regular language












3














for $A,Bsubseteq{0,1}^*$ regular languages



prove or disprove that $L_2$ is a regular language:



$L_2 = {x in A | exists y in B : |x|_1 =|y|_1 }$



$|x|_1$ means the number of appearances of 1 in the word.



if $L_2$ regular language demonstrate his automata, else disprove with pump lemma or with clousre properties.



I think $L_2$ is a regular language because I can choose $A=B$ for example and I'll get regular language or for example $B={0,1}^*$.



I am not sure how to demonstrate his automata.










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  • Are $A$ and $B$ regular languages? Also, I assume prove that "$L_2$ is a formal language" is a typo, since this would be trivial and doesn't match the title. Should it say "regular language"?
    – Joey Kilpatrick
    Nov 25 at 4:02












  • @JoeyKilpatrick you are right, edited.
    – UltimateMath
    Nov 25 at 7:43












  • Let $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$, then $L_2 = A cap B'$, can you find an automatum for $B'$?
    – Alex Vong
    Nov 25 at 8:01


















3














for $A,Bsubseteq{0,1}^*$ regular languages



prove or disprove that $L_2$ is a regular language:



$L_2 = {x in A | exists y in B : |x|_1 =|y|_1 }$



$|x|_1$ means the number of appearances of 1 in the word.



if $L_2$ regular language demonstrate his automata, else disprove with pump lemma or with clousre properties.



I think $L_2$ is a regular language because I can choose $A=B$ for example and I'll get regular language or for example $B={0,1}^*$.



I am not sure how to demonstrate his automata.










share|cite|improve this question
























  • Are $A$ and $B$ regular languages? Also, I assume prove that "$L_2$ is a formal language" is a typo, since this would be trivial and doesn't match the title. Should it say "regular language"?
    – Joey Kilpatrick
    Nov 25 at 4:02












  • @JoeyKilpatrick you are right, edited.
    – UltimateMath
    Nov 25 at 7:43












  • Let $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$, then $L_2 = A cap B'$, can you find an automatum for $B'$?
    – Alex Vong
    Nov 25 at 8:01
















3












3








3







for $A,Bsubseteq{0,1}^*$ regular languages



prove or disprove that $L_2$ is a regular language:



$L_2 = {x in A | exists y in B : |x|_1 =|y|_1 }$



$|x|_1$ means the number of appearances of 1 in the word.



if $L_2$ regular language demonstrate his automata, else disprove with pump lemma or with clousre properties.



I think $L_2$ is a regular language because I can choose $A=B$ for example and I'll get regular language or for example $B={0,1}^*$.



I am not sure how to demonstrate his automata.










share|cite|improve this question















for $A,Bsubseteq{0,1}^*$ regular languages



prove or disprove that $L_2$ is a regular language:



$L_2 = {x in A | exists y in B : |x|_1 =|y|_1 }$



$|x|_1$ means the number of appearances of 1 in the word.



if $L_2$ regular language demonstrate his automata, else disprove with pump lemma or with clousre properties.



I think $L_2$ is a regular language because I can choose $A=B$ for example and I'll get regular language or for example $B={0,1}^*$.



I am not sure how to demonstrate his automata.







formal-languages automata






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edited Nov 25 at 7:40

























asked Nov 24 at 22:09









UltimateMath

746




746












  • Are $A$ and $B$ regular languages? Also, I assume prove that "$L_2$ is a formal language" is a typo, since this would be trivial and doesn't match the title. Should it say "regular language"?
    – Joey Kilpatrick
    Nov 25 at 4:02












  • @JoeyKilpatrick you are right, edited.
    – UltimateMath
    Nov 25 at 7:43












  • Let $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$, then $L_2 = A cap B'$, can you find an automatum for $B'$?
    – Alex Vong
    Nov 25 at 8:01




















  • Are $A$ and $B$ regular languages? Also, I assume prove that "$L_2$ is a formal language" is a typo, since this would be trivial and doesn't match the title. Should it say "regular language"?
    – Joey Kilpatrick
    Nov 25 at 4:02












  • @JoeyKilpatrick you are right, edited.
    – UltimateMath
    Nov 25 at 7:43












  • Let $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$, then $L_2 = A cap B'$, can you find an automatum for $B'$?
    – Alex Vong
    Nov 25 at 8:01


















Are $A$ and $B$ regular languages? Also, I assume prove that "$L_2$ is a formal language" is a typo, since this would be trivial and doesn't match the title. Should it say "regular language"?
– Joey Kilpatrick
Nov 25 at 4:02






Are $A$ and $B$ regular languages? Also, I assume prove that "$L_2$ is a formal language" is a typo, since this would be trivial and doesn't match the title. Should it say "regular language"?
– Joey Kilpatrick
Nov 25 at 4:02














@JoeyKilpatrick you are right, edited.
– UltimateMath
Nov 25 at 7:43






@JoeyKilpatrick you are right, edited.
– UltimateMath
Nov 25 at 7:43














Let $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$, then $L_2 = A cap B'$, can you find an automatum for $B'$?
– Alex Vong
Nov 25 at 8:01






Let $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$, then $L_2 = A cap B'$, can you find an automatum for $B'$?
– Alex Vong
Nov 25 at 8:01












2 Answers
2






active

oldest

votes


















3














I am not entire sure if my approach work, but here we go:
Firstly, we observe that we can write $L_2 = A cap B'$ where $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$. Since we can create a FSA for the intersection of two regular languages, it suffices to find a FSA for $B'$.



Before proceeding, consider a more concrete description of $B'$. Note that we can write $$B' = {0^{alpha_0} 1 0^{alpha_1} 1 0^{alpha_2} dots 1 0^{alpha_{|y|_1}} mid alpha_j in mathbb{N}, y in B}$$ Intuitively, $B'$ is constructed by taking all strings in $B$, chops away all $0$'s, and adding back any number of $0$'s in between.



Now given a FSA $M$ for $B$, we can construct a corresponding FSA $M'$ for $B'$ by the following transformation:



Case 1:
B case 1
should be converted to
B' case 1



Case 2:
B case 2
Nothing needs to be changed.



Case 3:
B case 3
should be converted to
B' case 3



Case 4:
B case 4
Nothing needs to be changed.



This completes the FSA.






share|cite|improve this answer





























    2














    Let $pi: {0,1}^* to 1^*$ be the monoid morphism defined by $pi(u) = |u|_1$. Since regular languages are closed under morphisms and inverses of morphisms, $R =pi(B)$ is regular and $L_2 = A cap pi^{-1}(R)$ is regular.






    share|cite|improve this answer























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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      3














      I am not entire sure if my approach work, but here we go:
      Firstly, we observe that we can write $L_2 = A cap B'$ where $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$. Since we can create a FSA for the intersection of two regular languages, it suffices to find a FSA for $B'$.



      Before proceeding, consider a more concrete description of $B'$. Note that we can write $$B' = {0^{alpha_0} 1 0^{alpha_1} 1 0^{alpha_2} dots 1 0^{alpha_{|y|_1}} mid alpha_j in mathbb{N}, y in B}$$ Intuitively, $B'$ is constructed by taking all strings in $B$, chops away all $0$'s, and adding back any number of $0$'s in between.



      Now given a FSA $M$ for $B$, we can construct a corresponding FSA $M'$ for $B'$ by the following transformation:



      Case 1:
      B case 1
      should be converted to
      B' case 1



      Case 2:
      B case 2
      Nothing needs to be changed.



      Case 3:
      B case 3
      should be converted to
      B' case 3



      Case 4:
      B case 4
      Nothing needs to be changed.



      This completes the FSA.






      share|cite|improve this answer


























        3














        I am not entire sure if my approach work, but here we go:
        Firstly, we observe that we can write $L_2 = A cap B'$ where $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$. Since we can create a FSA for the intersection of two regular languages, it suffices to find a FSA for $B'$.



        Before proceeding, consider a more concrete description of $B'$. Note that we can write $$B' = {0^{alpha_0} 1 0^{alpha_1} 1 0^{alpha_2} dots 1 0^{alpha_{|y|_1}} mid alpha_j in mathbb{N}, y in B}$$ Intuitively, $B'$ is constructed by taking all strings in $B$, chops away all $0$'s, and adding back any number of $0$'s in between.



        Now given a FSA $M$ for $B$, we can construct a corresponding FSA $M'$ for $B'$ by the following transformation:



        Case 1:
        B case 1
        should be converted to
        B' case 1



        Case 2:
        B case 2
        Nothing needs to be changed.



        Case 3:
        B case 3
        should be converted to
        B' case 3



        Case 4:
        B case 4
        Nothing needs to be changed.



        This completes the FSA.






        share|cite|improve this answer
























          3












          3








          3






          I am not entire sure if my approach work, but here we go:
          Firstly, we observe that we can write $L_2 = A cap B'$ where $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$. Since we can create a FSA for the intersection of two regular languages, it suffices to find a FSA for $B'$.



          Before proceeding, consider a more concrete description of $B'$. Note that we can write $$B' = {0^{alpha_0} 1 0^{alpha_1} 1 0^{alpha_2} dots 1 0^{alpha_{|y|_1}} mid alpha_j in mathbb{N}, y in B}$$ Intuitively, $B'$ is constructed by taking all strings in $B$, chops away all $0$'s, and adding back any number of $0$'s in between.



          Now given a FSA $M$ for $B$, we can construct a corresponding FSA $M'$ for $B'$ by the following transformation:



          Case 1:
          B case 1
          should be converted to
          B' case 1



          Case 2:
          B case 2
          Nothing needs to be changed.



          Case 3:
          B case 3
          should be converted to
          B' case 3



          Case 4:
          B case 4
          Nothing needs to be changed.



          This completes the FSA.






          share|cite|improve this answer












          I am not entire sure if my approach work, but here we go:
          Firstly, we observe that we can write $L_2 = A cap B'$ where $B' = {s in Sigma^* mid |s|_1 = |y|_1 text{ for some } y in B}$. Since we can create a FSA for the intersection of two regular languages, it suffices to find a FSA for $B'$.



          Before proceeding, consider a more concrete description of $B'$. Note that we can write $$B' = {0^{alpha_0} 1 0^{alpha_1} 1 0^{alpha_2} dots 1 0^{alpha_{|y|_1}} mid alpha_j in mathbb{N}, y in B}$$ Intuitively, $B'$ is constructed by taking all strings in $B$, chops away all $0$'s, and adding back any number of $0$'s in between.



          Now given a FSA $M$ for $B$, we can construct a corresponding FSA $M'$ for $B'$ by the following transformation:



          Case 1:
          B case 1
          should be converted to
          B' case 1



          Case 2:
          B case 2
          Nothing needs to be changed.



          Case 3:
          B case 3
          should be converted to
          B' case 3



          Case 4:
          B case 4
          Nothing needs to be changed.



          This completes the FSA.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 25 at 12:05









          Alex Vong

          1,227819




          1,227819























              2














              Let $pi: {0,1}^* to 1^*$ be the monoid morphism defined by $pi(u) = |u|_1$. Since regular languages are closed under morphisms and inverses of morphisms, $R =pi(B)$ is regular and $L_2 = A cap pi^{-1}(R)$ is regular.






              share|cite|improve this answer




























                2














                Let $pi: {0,1}^* to 1^*$ be the monoid morphism defined by $pi(u) = |u|_1$. Since regular languages are closed under morphisms and inverses of morphisms, $R =pi(B)$ is regular and $L_2 = A cap pi^{-1}(R)$ is regular.






                share|cite|improve this answer


























                  2












                  2








                  2






                  Let $pi: {0,1}^* to 1^*$ be the monoid morphism defined by $pi(u) = |u|_1$. Since regular languages are closed under morphisms and inverses of morphisms, $R =pi(B)$ is regular and $L_2 = A cap pi^{-1}(R)$ is regular.






                  share|cite|improve this answer














                  Let $pi: {0,1}^* to 1^*$ be the monoid morphism defined by $pi(u) = |u|_1$. Since regular languages are closed under morphisms and inverses of morphisms, $R =pi(B)$ is regular and $L_2 = A cap pi^{-1}(R)$ is regular.







                  share|cite|improve this answer














                  share|cite|improve this answer



                  share|cite|improve this answer








                  edited Nov 25 at 12:22

























                  answered Nov 25 at 11:23









                  J.-E. Pin

                  18.3k21754




                  18.3k21754






























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