A354492 -id:A354492 - cp's OEIS frontend

A354702 T(w,h) is an upper bound for the minimum number of grid points in a square grid covered by an arbitrarily positioned and rotated rectangle of width w and height h, where T(w,h) is a triangle read by rows.

0, 1, 2, 2, 4, 7, 2, 5, 9, 12, 3, 7, 13, 17, 21, 4, 8, 15, 20, 26, 32, 4, 9, 18, 22, 31, 36, 40, 5, 11, 20, 27, 36, 44, 49, 57, 6, 12, 24, 30, 41, 48, 54, 66, 72, 7, 14, 26, 35, 46, 55, 63, 74, 84, 96, 7, 15, 28, 37, 50, 60, 67, 81, 90, 105, 112, 8, 16, 31, 40, 55, 64, 72, 88, 96, 112, 120, 128

Offset: 1

Hugo Pfoertner, Jun 15 2022

Grid points must lie strictly within the covering rectangle, i.e., grid points on the perimeter of the rectangle are not allowed.
These upper bounds were determined by an extensive random search, the results of which were stable. The proof that none of these bounds can be improved should be possible with a constructive technique such as integer linear programming applied to all combinatorially possible positions of the rectangle relative to the lattice.
A simple random search is implemented in the attached PARI program, which enables a plausibility check of the results for small covering rectangles. It also provides results for the maximum problem. Additional methods were used to obtain the results shown. In particular, angular orientations of the rectangle along connecting lines between all pairs of lattice points and extreme positions of the rectangle, where lattice points are very close to the corners of the rectangle, were investigated, using adjacent terms in A000404.

			The triangle begins:
    \ h 1   2   3   4   5   6   7   8   9   10   11   12
   w \ -------------------------------------------------
   1 |  0;  |   |   |   |   |   |   |   |    |    |    |
   2 |  1,  2;  |   |   |   |   |   |   |    |    |    |
   3 |  2,  4,  7;  |   |   |   |   |   |    |    |    |
   4 |  2,  5,  9, 12;  |   |   |   |   |    |    |    |
   5 |  3,  7, 13, 17, 21;  |   |   |   |    |    |    |
   6 |  4,  8, 15, 20, 26, 32;  |   |   |    |    |    |
   7 |  4,  9, 18, 22, 31, 36, 40;  |   |    |    |    |
   8 |  5, 11, 20, 27, 36, 44, 49, 57;  |    |    |    |
   9 |  6, 12, 24, 30, 41, 48, 54, 66, 72;   |    |    |
  10 |  7, 14, 26, 35, 46, 55, 63, 74, 84,  96;   |    |
  11 |  7, 15, 28, 37, 50, 60, 67, 81, 90, 105, 112;   |
  12 |  8, 16, 31, 40, 55, 64, 72, 88, 96, 112, 120, 128

Hugo Pfoertner, Table of n, a(n) for n = 1..210, rows 1..20 of triangle, flattened
Hugo Pfoertner, Illustrations of the initial terms up to T(5,5).
Hugo Pfoertner, PARI program

Cf. A293330 (diagonal).
Cf. A354492, A354703, A354704, A354705, A355241, A355242.
Cf. A291259 (similar problem for circular disks).
Cf. A000404 (used to check extreme positions of grid points).

PARI
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\\ See link.
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PARI
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\\ See also program link in A355241.
```

A354703 T(w,h) = w*h - A354702(w,h) is a lower bound on the gain in the number of not covered grid points from an optimally positioned and rotated cover versus a just translated cover, where T(w,h) and A354702 are triangles read by rows.

Original entry on oeis.org

1, 1, 2, 1, 2, 2, 2, 3, 3, 4, 2, 3, 2, 3, 4, 2, 4, 3, 4, 4, 4, 3, 5, 3, 6, 4, 6, 9, 3, 5, 4, 5, 4, 4, 7, 7, 3, 6, 3, 6, 4, 6, 9, 6, 9, 3, 6, 4, 5, 4, 5, 7, 6, 6, 4, 4, 7, 5, 7, 5, 6, 10, 7, 9, 5, 9, 4, 8, 5, 8, 5, 8, 12, 8, 12, 8, 12, 16, 4, 8, 5, 7, 4, 6, 10, 6, 9, 4, 8, 12, 7

Offset: 1

Hugo Pfoertner, Jun 15 2022

			The triangle begins:
    \ h 1  2  3  4  5  6   7  8   9 10  11  12 13
   w \ ------------------------------------------
   1 |  1; |  |  |  |  |   |  |   |  |   |   |  |
   2 |  1, 2; |  |  |  |   |  |   |  |   |   |  |
   3 |  1, 2, 2; |  |  |   |  |   |  |   |   |  |
   4 |  2, 3, 3, 4; |  |   |  |   |  |   |   |  |
   5 |  2, 3, 2, 3, 4; |   |  |   |  |   |   |  |
   6 |  2, 4, 3, 4, 4, 4;  |  |   |  |   |   |  |
   7 |  3, 5, 3, 6, 4, 6,  9; |   |  |   |   |  |
   8 |  3, 5, 4, 5, 4, 4,  7, 7;  |  |   |   |  |
   9 |  3, 6, 3, 6, 4, 6,  9, 6,  9; |   |   |  |
  10 |  3, 6, 4, 5, 4, 5,  7, 6,  6, 4;  |   |  |
  11 |  4, 7, 5, 7, 5, 6, 10, 7,  9, 5,  9;  |  |
  12 |  4, 8, 5, 8, 5, 8, 12, 8, 12, 8, 12, 16; |
  13 |  4, 8, 5, 7, 4, 6, 10, 6,  9, 4,  8, 12, 7
.
T(4,3) = 3, because the optimally positioned and rotated 4 X 3 rectangle
covers A354702(4,3) = 9 grid points, whereas a translated, but unrotated 4 X 3 rectangle covers 4*3 = 12 grid points. 4*3 - 9 = 3.
  + . . . . + . . . . + . . . . + . . . . + . . . . + . . . . +
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  + . . . . \ . . . . 8 . . . . 9 . . . . + . . . . + . . . . +
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  .         .     O   .         .         .         .         .
  .         .         .         .         .         .
  .     O---------o---------o---------o---------O   .
  .     |   .         .         .         .     |   .
  + . . | . 1 . . . . 2 . . . . 3 . . . . 4 . . | . +
  .     |   .         .         .         .     |   .
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  .     o   .         .         .         .     o   .
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  + . . | . 5 . . . . 6 . . . . 7 . . . . 8 . . | . +
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  + . . | . 9 . . . .10 . . . .11 . . . .12 . . | . +
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  .     O---------o---------o---------o---------O   .
  .         .         .         .         .         .
  + . . . . + . . . . + . . . . + . . . . + . . . . +

Hugo Pfoertner, Table of n, a(n) for n = 1..210, rows 1..20 of triangle, flattened

Cf. A354702, A354492 (diagonal).

Cf. A354704, A354705 (similar, but for maximizing the number of covered points).

A354707 Diagonal of A354705.

Original entry on oeis.org

2, 4, 3, 7, 4, 8, 11, 9, 11, 8, 16, 20, 15, 20, 14, 24, 11, 23, 27, 20, 34, 17, 31, 41, 28, 32

Offset: 1

Hugo Pfoertner, Jun 21 2022

a(n)-n is an indicator of whether there is still space between the covered grid points and the best possible placed square towards its perimeter. a(n)-n <= 0 for n = 3, 5, 10, 15, 17, 20, 22, ... . A comparison with the linked illustrations from A354706 shows that in all these cases the covering square is rotated by Pi/4 and only slightly exceeds diagonal rows of grid points on all its edges.

Hugo Pfoertner, Illustrations of diagonal terms A354704(1,1)..A354704(22,22).

Cf. A354704, A354705, A354706.

A354492 is the analogous sequence, but for the problem of minimizing the number of grid points covered.

cp's OEIS Frontend

A354702 T(w,h) is an upper bound for the minimum number of grid points in a square grid covered by an arbitrarily positioned and rotated rectangle of width w and height h, where T(w,h) is a triangle read by rows.

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A354703 T(w,h) = w*h - A354702(w,h) is a lower bound on the gain in the number of not covered grid points from an optimally positioned and rotated cover versus a just translated cover, where T(w,h) and A354702 are triangles read by rows.

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Author

Keywords

Examples

Links

Crossrefs

A354707 Diagonal of A354705.

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