What is the minimum distance between vertices on an integer grid with the form $(m(m+2), 0)p + (m, 1)q$?












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Suppose, for given $m > 0$, we have a set of points of the form $v = (m(m+2), 0)p + (m, 1)q$, with $p, q, m$ integers. What is the minimum distance between two (distinct ones) of them?



Here is the square distance between any point and the origin:
$|v|^2 = (pm^2 + 2pm + qm)^2 + q^2,$



we need to find the $p, q$ that minimizes this distance given $m > 0$.



In practice it is easy enough to check a few points, and find the optimum by trial and error, but I am wondering if there is a closed form solution.



Background: this came up while working on this question: How many colors is necessary so that a rectangle always covers no color more than once?. See the second last conjecture.



(Note: I am not sure if there are more appropriate tags.)










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    0












    $begingroup$


    Suppose, for given $m > 0$, we have a set of points of the form $v = (m(m+2), 0)p + (m, 1)q$, with $p, q, m$ integers. What is the minimum distance between two (distinct ones) of them?



    Here is the square distance between any point and the origin:
    $|v|^2 = (pm^2 + 2pm + qm)^2 + q^2,$



    we need to find the $p, q$ that minimizes this distance given $m > 0$.



    In practice it is easy enough to check a few points, and find the optimum by trial and error, but I am wondering if there is a closed form solution.



    Background: this came up while working on this question: How many colors is necessary so that a rectangle always covers no color more than once?. See the second last conjecture.



    (Note: I am not sure if there are more appropriate tags.)










    share|cite|improve this question











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      0








      0





      $begingroup$


      Suppose, for given $m > 0$, we have a set of points of the form $v = (m(m+2), 0)p + (m, 1)q$, with $p, q, m$ integers. What is the minimum distance between two (distinct ones) of them?



      Here is the square distance between any point and the origin:
      $|v|^2 = (pm^2 + 2pm + qm)^2 + q^2,$



      we need to find the $p, q$ that minimizes this distance given $m > 0$.



      In practice it is easy enough to check a few points, and find the optimum by trial and error, but I am wondering if there is a closed form solution.



      Background: this came up while working on this question: How many colors is necessary so that a rectangle always covers no color more than once?. See the second last conjecture.



      (Note: I am not sure if there are more appropriate tags.)










      share|cite|improve this question











      $endgroup$




      Suppose, for given $m > 0$, we have a set of points of the form $v = (m(m+2), 0)p + (m, 1)q$, with $p, q, m$ integers. What is the minimum distance between two (distinct ones) of them?



      Here is the square distance between any point and the origin:
      $|v|^2 = (pm^2 + 2pm + qm)^2 + q^2,$



      we need to find the $p, q$ that minimizes this distance given $m > 0$.



      In practice it is easy enough to check a few points, and find the optimum by trial and error, but I am wondering if there is a closed form solution.



      Background: this came up while working on this question: How many colors is necessary so that a rectangle always covers no color more than once?. See the second last conjecture.



      (Note: I am not sure if there are more appropriate tags.)







      integer-programming






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      edited Dec 14 '18 at 22:57







      Herman Tulleken

















      asked Dec 14 '18 at 22:36









      Herman TullekenHerman Tulleken

      968620




      968620






















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          $begingroup$

          Since $v^2$ is a sum of squares of integers, and it's not $0$, then it must be $1$ (if we can find such a solution). There are two choices:



          Case 1: $q=0$ and $pm^2+2pm+qm=pm1$. I can easily guess a solution for
          $pm^2+2pm=-1$: $p=1$ and $m=-1$



          Case 2: $q=pm 1$ and $pm^2+2pm+qm=0$. Same $p$ and $m$ as above also verify this case.






          share|cite|improve this answer









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          • $begingroup$
            I realized now my question did not specify to find $p, q$ given $m$. I will update my question.
            $endgroup$
            – Herman Tulleken
            Dec 14 '18 at 22:55











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          0












          $begingroup$

          Since $v^2$ is a sum of squares of integers, and it's not $0$, then it must be $1$ (if we can find such a solution). There are two choices:



          Case 1: $q=0$ and $pm^2+2pm+qm=pm1$. I can easily guess a solution for
          $pm^2+2pm=-1$: $p=1$ and $m=-1$



          Case 2: $q=pm 1$ and $pm^2+2pm+qm=0$. Same $p$ and $m$ as above also verify this case.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I realized now my question did not specify to find $p, q$ given $m$. I will update my question.
            $endgroup$
            – Herman Tulleken
            Dec 14 '18 at 22:55
















          0












          $begingroup$

          Since $v^2$ is a sum of squares of integers, and it's not $0$, then it must be $1$ (if we can find such a solution). There are two choices:



          Case 1: $q=0$ and $pm^2+2pm+qm=pm1$. I can easily guess a solution for
          $pm^2+2pm=-1$: $p=1$ and $m=-1$



          Case 2: $q=pm 1$ and $pm^2+2pm+qm=0$. Same $p$ and $m$ as above also verify this case.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I realized now my question did not specify to find $p, q$ given $m$. I will update my question.
            $endgroup$
            – Herman Tulleken
            Dec 14 '18 at 22:55














          0












          0








          0





          $begingroup$

          Since $v^2$ is a sum of squares of integers, and it's not $0$, then it must be $1$ (if we can find such a solution). There are two choices:



          Case 1: $q=0$ and $pm^2+2pm+qm=pm1$. I can easily guess a solution for
          $pm^2+2pm=-1$: $p=1$ and $m=-1$



          Case 2: $q=pm 1$ and $pm^2+2pm+qm=0$. Same $p$ and $m$ as above also verify this case.






          share|cite|improve this answer









          $endgroup$



          Since $v^2$ is a sum of squares of integers, and it's not $0$, then it must be $1$ (if we can find such a solution). There are two choices:



          Case 1: $q=0$ and $pm^2+2pm+qm=pm1$. I can easily guess a solution for
          $pm^2+2pm=-1$: $p=1$ and $m=-1$



          Case 2: $q=pm 1$ and $pm^2+2pm+qm=0$. Same $p$ and $m$ as above also verify this case.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 14 '18 at 22:51









          AndreiAndrei

          12.6k21128




          12.6k21128












          • $begingroup$
            I realized now my question did not specify to find $p, q$ given $m$. I will update my question.
            $endgroup$
            – Herman Tulleken
            Dec 14 '18 at 22:55


















          • $begingroup$
            I realized now my question did not specify to find $p, q$ given $m$. I will update my question.
            $endgroup$
            – Herman Tulleken
            Dec 14 '18 at 22:55
















          $begingroup$
          I realized now my question did not specify to find $p, q$ given $m$. I will update my question.
          $endgroup$
          – Herman Tulleken
          Dec 14 '18 at 22:55




          $begingroup$
          I realized now my question did not specify to find $p, q$ given $m$. I will update my question.
          $endgroup$
          – Herman Tulleken
          Dec 14 '18 at 22:55


















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