First-order logic formula(prime numbers)












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How to write into a first-order logic formula:



1) $m$ is prime number, which consists in $[sqrt{n},n]$



2) $n$ is number of second power of prime number.



$textbf{My work:}$



Prime number can be written like: $prime(x) = 1<x, wedge, forall u, v (x = u cdot v rightarrow u = 1 vee v =1)$.



2) I think that in this case it can be written like $n = 1<n, wedge, forall u, v (n = ucdot u cdot v cdot v rightarrow u = 1 vee v =1)$, but Im not sure



1) Here I have no idea, how to do it...










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    0














    How to write into a first-order logic formula:



    1) $m$ is prime number, which consists in $[sqrt{n},n]$



    2) $n$ is number of second power of prime number.



    $textbf{My work:}$



    Prime number can be written like: $prime(x) = 1<x, wedge, forall u, v (x = u cdot v rightarrow u = 1 vee v =1)$.



    2) I think that in this case it can be written like $n = 1<n, wedge, forall u, v (n = ucdot u cdot v cdot v rightarrow u = 1 vee v =1)$, but Im not sure



    1) Here I have no idea, how to do it...










    share|cite|improve this question

























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      0







      How to write into a first-order logic formula:



      1) $m$ is prime number, which consists in $[sqrt{n},n]$



      2) $n$ is number of second power of prime number.



      $textbf{My work:}$



      Prime number can be written like: $prime(x) = 1<x, wedge, forall u, v (x = u cdot v rightarrow u = 1 vee v =1)$.



      2) I think that in this case it can be written like $n = 1<n, wedge, forall u, v (n = ucdot u cdot v cdot v rightarrow u = 1 vee v =1)$, but Im not sure



      1) Here I have no idea, how to do it...










      share|cite|improve this question













      How to write into a first-order logic formula:



      1) $m$ is prime number, which consists in $[sqrt{n},n]$



      2) $n$ is number of second power of prime number.



      $textbf{My work:}$



      Prime number can be written like: $prime(x) = 1<x, wedge, forall u, v (x = u cdot v rightarrow u = 1 vee v =1)$.



      2) I think that in this case it can be written like $n = 1<n, wedge, forall u, v (n = ucdot u cdot v cdot v rightarrow u = 1 vee v =1)$, but Im not sure



      1) Here I have no idea, how to do it...







      logic first-order-logic






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      asked Dec 10 '18 at 20:20









      Aleksandra

      565




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          Hints:



          For (1), $m in [sqrt{n}, n]$ iff $n le m^2 le n^2$.



          For (2), it is much simpler to use an existential quantifier to express the property that there exists a prime, $p$, such that $n = p^2$. Your suggestion involves a neat idea but it doesn't quite work, e.g., your predicate holds if $n$ is not a square, because then there are no $u$ and $v$ such that $n = u^2v^2$.






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            1 Answer
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            1 Answer
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            active

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            0














            Hints:



            For (1), $m in [sqrt{n}, n]$ iff $n le m^2 le n^2$.



            For (2), it is much simpler to use an existential quantifier to express the property that there exists a prime, $p$, such that $n = p^2$. Your suggestion involves a neat idea but it doesn't quite work, e.g., your predicate holds if $n$ is not a square, because then there are no $u$ and $v$ such that $n = u^2v^2$.






            share|cite|improve this answer


























              0














              Hints:



              For (1), $m in [sqrt{n}, n]$ iff $n le m^2 le n^2$.



              For (2), it is much simpler to use an existential quantifier to express the property that there exists a prime, $p$, such that $n = p^2$. Your suggestion involves a neat idea but it doesn't quite work, e.g., your predicate holds if $n$ is not a square, because then there are no $u$ and $v$ such that $n = u^2v^2$.






              share|cite|improve this answer
























                0












                0








                0






                Hints:



                For (1), $m in [sqrt{n}, n]$ iff $n le m^2 le n^2$.



                For (2), it is much simpler to use an existential quantifier to express the property that there exists a prime, $p$, such that $n = p^2$. Your suggestion involves a neat idea but it doesn't quite work, e.g., your predicate holds if $n$ is not a square, because then there are no $u$ and $v$ such that $n = u^2v^2$.






                share|cite|improve this answer












                Hints:



                For (1), $m in [sqrt{n}, n]$ iff $n le m^2 le n^2$.



                For (2), it is much simpler to use an existential quantifier to express the property that there exists a prime, $p$, such that $n = p^2$. Your suggestion involves a neat idea but it doesn't quite work, e.g., your predicate holds if $n$ is not a square, because then there are no $u$ and $v$ such that $n = u^2v^2$.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 10 '18 at 20:39









                Rob Arthan

                29.1k42866




                29.1k42866






























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