MatsGranvik

Linear programming Square root bounds and Harmonic numbers

Jun 6th, 2019
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  1. (*Numerators of the partial sums of the Möbius inverse of the Harmonic numbers*)
  2. (*start*)
  3. Clear[T, n, k, a];
  4. nn = 7;
  5. a[n_] := If[n < 1, 0, Sum[d MoebiusMu@d, {d, Divisors[n]}]]
  6. TableForm[
  7. M = Table[
  8. Table[Sum[If[n >= k, a[GCD[n, k]], 0], {n, 1, m}], {k, 1, nn}], {m,
  9. 1, nn}]]
  10. (*end*)
  11.  
  12. (*The partial sums of the Möbius inverse of the Harmonic numbers fit within this linear programming problem*)
  13. (*start*)
  14. nn = 42;
  15. TableForm[
  16. L1 = Table[
  17. LinearProgramming[
  18. Table[1/n, {n, 1, k}], {Table[If[n == 1, k, 1], {n, 1, k}]}, {{1,
  19. 0}}, Table[
  20. If[n == 1, {-1, 1}, {-2 (n - 1), 2 (n - 1)}], {n, 1, k}]], {k,
  21. 1, nn}]];
  22. b = Table[Sum[-Sign[-1 + Sign[L1[[n, k]]]], {k, 1, n}], {n, 1, nn}]
  23. (*end*)
  24.  
  25. (*Setting the upper bound on the variables to zero gives us a square root bound, but then it is no longer an
  26. arithmetic sequence.*)
  27. (*start*)
  28. nn = 42;
  29. TableForm[
  30. L2 = Table[
  31. LinearProgramming[
  32. Table[1/n, {n, 1, k}], {Table[If[n == 1, k, 1], {n, 1, k}]}, {{1,
  33. 0}}, Table[
  34. If[n == 1, {-1, 1}, {-2 (n - 1), 0}], {n, 1, k}]], {k, 1, nn}]];
  35. c = Table[1 - Sum[Sign[L2[[n, k]]], {k, 1, n}], {n, 1, nn}]
  36. (*end*)
  37.  
  38. (*Numerators of the partial sums of the Möbius inverse of the \
  39. Harmonic numbers*)
  40. (*start*)
  41. Clear[T, n, k, a, b];
  42. nn = 8;
  43. a[n_] := If[n < 1, 0, Sum[d MoebiusMu@d, {d, Divisors[n]}]]
  44. TableForm[
  45. Table[Table[If[n >= k, a[GCD[n, k]], 0], {k, 1, nn}], {n, 1, nn}]];
  46. TableForm[
  47. M = Table[
  48. Table[If[n >= k, StringJoin["a", ToString[n], ToString[k]],
  49. 0], {k, 1, nn}], {n, 1, nn}]];
  50. TableForm[
  51. Table[Table[
  52. Table[M[[m, k]], {m, n + k - 1, n + 2*(k - 1)}], {n, 1,
  53. nn - 2*(k - 1)}], {k, 1, nn}]];
  54. TableForm[
  55. Table[Table[
  56. Table[StringJoin[
  57. ToString[Sum[M[[m, k]], {m, n + k - 1, n + 2*(k - 1)}]],
  58. If[k == 1, "==1", StringJoin["==", ToString[0*2*(k - 1)]]]], {n,
  59. 1, nn - 2*(k - 1)}], {k, 1, nn}], {nn, 1, nn}]];
  60. TableForm[
  61. B = Table[
  62. Table[StringJoin[
  63. ToString[
  64. Sum[Sum[M[[m, k]], {m, n + k - 1, n + 2*(k - 1)}], {n, 1,
  65. nn - 2*(k - 1)}]],
  66. If[k == 1, "==1", StringJoin["<=", ToString[2*(k - 1)]]]], {k,
  67. 1, nn}], {nn, 1, nn}]];
  68. "Some of the constraints"
  69. TableForm[
  70. B1 = Table[
  71. Table[StringJoin[
  72. ToString[
  73. Sum[Sum[M[[m, k]], {m, n + k - 1, n + 2*(k - 1)}], {n, 1,
  74. nn - 2*(k - 1)}]], If[k == 1, "==1", "<="],
  75. ToString[2*(k - 1)]], {k, 1, nn}], {nn, 1, nn}]]
  76. TableForm[
  77. B1 = Table[
  78. Table[StringJoin[
  79. ToString[
  80. Sum[Sum[M[[m, k]], {m, n + k - 1, n + 2*(k - 1)}], {n, 1,
  81. nn - 2*(k - 1)}]], If[k == 1, "==1", "=>"],
  82. ToString[-2*(k - 1)]], {k, 1, nn}], {nn, 1, nn}]]
  83. TableForm[
  84. B1 = Table[
  85. Table[StringJoin[
  86. ToString[
  87. Sum[Sum[M[[m, k]], {m, n + k - 1, n + 2*(k - 1)}], {n, 1,
  88. nn - 2*(k - 1)}]]], {k, 1, nn}], {nn, 1, nn}]];
  89. TableForm[
  90. B2 = Table[
  91. StringJoin[
  92. ToString[Sum[StringJoin[ToString[B1[[n, k]]]], {k, 1, n}]],
  93. "==1"], {n, 1, nn}]]
  94. "Maximize this:"
  95. TableForm[
  96. B3 = Table[
  97. StringJoin[
  98. ToString[
  99. Sum[StringJoin["(", ToString[B1[[n, k]]], ")/", ToString[k]], {k,
  100. 1, n}]]], {n, 1, nn}]]
  101. (*end*)
  102.  
  103. (*start*)
  104. "For larger epsilons we get non zero differences"
  105. epsilon = 1/100;
  106. Table[Floor[x^(1/2 + epsilon) + 1/2] - Floor[x^(1/2) + 1/2], {x, 0,
  107. 400}]
  108.  
  109. "For smaller epsilons we get zero"
  110. epsilon = 1/100000000;
  111. Table[Floor[x^(1/2 + epsilon) + 1/2] - Floor[x^(1/2) + 1/2], {x, 0,
  112. 400}]
  113. (*end*)
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