Writing a formal description for F to prove recursion.












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$begingroup$


I am making an update for finding a formal description using the language of recursion to show that the following is recursive:



$left{begin{matrix}
F(0,y,z)=G(y)\
F(x+1,y,z)=H(z,F(x,y,z))
end{matrix}right.$



One of my classmates helped me come up with this:



Since $H$ depends on $F$, define a new description $bar{mathbf{F}}(y,z,x)$, where $bar{F}(y,z,0)=bar{G}(y,z)=G(y)$ and $bar{F}(y,z,x+1)=bar{H}(y,z,x,bar{F}(y,z,x))=
H(z,bar{F}(y,z,x))$
. Then $mathbf{F}=mathbf{C}(bar{mathbf{F}},mathbf{I}_{3,3},mathbf{I}_{3,1},mathbf{I}_{3,2})$, and $mathbf{bar{F}}=mathbf{P}(bar{mathbf{G}},mathbf{bar{H}})$, where $mathbf{bar{G}}=mathbf{C}(mathbf{G},mathbf{I}_{2,1})$ and $mathbf{bar{H}}=mathbf{C}(mathbf{H},mathbf{I}_{4,2},mathbf{I}_{4,4})$, describes F.



I am wondering whether this description is correct, and if so, can someone explain why $bar{F}(y,z,0)=bar{G}(y,z)=G(y)$ and $bar{F}(y,z,x+1)=bar{H}(y,z,x,bar{F}(y,z,x))=
H(z,bar{F}(y,z,x))$
? This is the only part I don't understand.










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$endgroup$

















    0












    $begingroup$


    I am making an update for finding a formal description using the language of recursion to show that the following is recursive:



    $left{begin{matrix}
    F(0,y,z)=G(y)\
    F(x+1,y,z)=H(z,F(x,y,z))
    end{matrix}right.$



    One of my classmates helped me come up with this:



    Since $H$ depends on $F$, define a new description $bar{mathbf{F}}(y,z,x)$, where $bar{F}(y,z,0)=bar{G}(y,z)=G(y)$ and $bar{F}(y,z,x+1)=bar{H}(y,z,x,bar{F}(y,z,x))=
    H(z,bar{F}(y,z,x))$
    . Then $mathbf{F}=mathbf{C}(bar{mathbf{F}},mathbf{I}_{3,3},mathbf{I}_{3,1},mathbf{I}_{3,2})$, and $mathbf{bar{F}}=mathbf{P}(bar{mathbf{G}},mathbf{bar{H}})$, where $mathbf{bar{G}}=mathbf{C}(mathbf{G},mathbf{I}_{2,1})$ and $mathbf{bar{H}}=mathbf{C}(mathbf{H},mathbf{I}_{4,2},mathbf{I}_{4,4})$, describes F.



    I am wondering whether this description is correct, and if so, can someone explain why $bar{F}(y,z,0)=bar{G}(y,z)=G(y)$ and $bar{F}(y,z,x+1)=bar{H}(y,z,x,bar{F}(y,z,x))=
    H(z,bar{F}(y,z,x))$
    ? This is the only part I don't understand.










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      I am making an update for finding a formal description using the language of recursion to show that the following is recursive:



      $left{begin{matrix}
      F(0,y,z)=G(y)\
      F(x+1,y,z)=H(z,F(x,y,z))
      end{matrix}right.$



      One of my classmates helped me come up with this:



      Since $H$ depends on $F$, define a new description $bar{mathbf{F}}(y,z,x)$, where $bar{F}(y,z,0)=bar{G}(y,z)=G(y)$ and $bar{F}(y,z,x+1)=bar{H}(y,z,x,bar{F}(y,z,x))=
      H(z,bar{F}(y,z,x))$
      . Then $mathbf{F}=mathbf{C}(bar{mathbf{F}},mathbf{I}_{3,3},mathbf{I}_{3,1},mathbf{I}_{3,2})$, and $mathbf{bar{F}}=mathbf{P}(bar{mathbf{G}},mathbf{bar{H}})$, where $mathbf{bar{G}}=mathbf{C}(mathbf{G},mathbf{I}_{2,1})$ and $mathbf{bar{H}}=mathbf{C}(mathbf{H},mathbf{I}_{4,2},mathbf{I}_{4,4})$, describes F.



      I am wondering whether this description is correct, and if so, can someone explain why $bar{F}(y,z,0)=bar{G}(y,z)=G(y)$ and $bar{F}(y,z,x+1)=bar{H}(y,z,x,bar{F}(y,z,x))=
      H(z,bar{F}(y,z,x))$
      ? This is the only part I don't understand.










      share|cite|improve this question









      $endgroup$




      I am making an update for finding a formal description using the language of recursion to show that the following is recursive:



      $left{begin{matrix}
      F(0,y,z)=G(y)\
      F(x+1,y,z)=H(z,F(x,y,z))
      end{matrix}right.$



      One of my classmates helped me come up with this:



      Since $H$ depends on $F$, define a new description $bar{mathbf{F}}(y,z,x)$, where $bar{F}(y,z,0)=bar{G}(y,z)=G(y)$ and $bar{F}(y,z,x+1)=bar{H}(y,z,x,bar{F}(y,z,x))=
      H(z,bar{F}(y,z,x))$
      . Then $mathbf{F}=mathbf{C}(bar{mathbf{F}},mathbf{I}_{3,3},mathbf{I}_{3,1},mathbf{I}_{3,2})$, and $mathbf{bar{F}}=mathbf{P}(bar{mathbf{G}},mathbf{bar{H}})$, where $mathbf{bar{G}}=mathbf{C}(mathbf{G},mathbf{I}_{2,1})$ and $mathbf{bar{H}}=mathbf{C}(mathbf{H},mathbf{I}_{4,2},mathbf{I}_{4,4})$, describes F.



      I am wondering whether this description is correct, and if so, can someone explain why $bar{F}(y,z,0)=bar{G}(y,z)=G(y)$ and $bar{F}(y,z,x+1)=bar{H}(y,z,x,bar{F}(y,z,x))=
      H(z,bar{F}(y,z,x))$
      ? This is the only part I don't understand.







      logic recursion computability






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      asked Dec 4 '18 at 22:56









      numericalorangenumericalorange

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