P82 · Packing and covering · Classic · Hard

Equal circles in regular polygons · m = 8 · n = 40

Pack n equal circles into the regular m-gon with centre (1,1), circumradius 1, and first vertex (2,1) so as to maximise their common radius.

Instancem = 8 · n = 40
ObjectiveMaximize circle radius

Record comparison

circle radius · Higher is better
RecordValue / intervalAuthor / holderSource
External best known[0.132682454148, 0.13268245415]Paolo AmorePackomania ↗
Site recordNo player record yet——

Formal definition

  • ContainerThe editor and certificate normalise the container to the exact regular m-gon with centre (1,1), circumradius 1, and first vertex (2,1), while public scores follow the literature convention. Boundary contact is allowed.
  • SubmissionSubmit {radius, placements:[{x,y,turn},…]}, with each value written as a decimal string of at most nine places. Here x, y are centre coordinates; circles require turn = 0 and polygons use turn = tan(θ/2). Coordinates and turn must lie in [−4, 4], with 0 < radius ≤ 4.
  • ConstraintsExactly n congruent pieces lie wholly inside the container with pairwise disjoint interiors. Polygons may rotate independently by arbitrary angles.
  • PrecisionInput decimals are parsed as exact rationals and regular-polygon vertices are defined algebraically, with zero floating-point tolerance in feasibility checks.
  • ObjectiveMaximise the circle radius r (with container circumradius fixed at 1).
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Layout shown: starter layout

VERIFIED CONSTRUCTIONVERIFIED CONSTRUCTION

Getting a feel for it

Literature targets and coordinate certificates

Literature targets are converted at their published precision, while nine-decimal coordinate certificates are stored and displayed alongside the source values. Pentagon and hexagon rows n = 41–100 and octagon rows n = 41–48 cite Packomania's value and author without importing its coordinates; they start from an ordinary site grid baseline.

Source
The current arrangement for Equal circles in regular polygons m = 8 · n = 40
LAYOUT & HISTORY

Starter layout

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ANSWER FORMAT

How to write your answer

the regular m-gon with centre (1,1), circumradius 1, and first vertex (2,1)

Submit {radius, placements:[{x,y,turn},…]}, with each value written as a decimal string of at most nine places. Here x, y are centre coordinates; circles require turn = 0 and polygons use turn = tan(θ/2). Coordinates and turn must lie in [−4, 4], with 0 < radius ≤ 4.

Starter answer

{
  "placements": [
    {
      "turn": "0",
      "x": "0.583604542",
      "y": "0.316091100"
    },
    {
      "turn": "0",
      "x": "0.828769749",
      "y": "0.214540346"
    },
    {
      "turn": "0",
      "x": "0.364742185",
      "y": "0.466150432"
    },
    {
      "turn": "0",
      "x": "1.092102790",
      "y": "0.181764678"
    },
    {
      "turn": "0",
      "x": "0.263191431",
      "y": "0.711315639"
    },
    {
      "turn": "0",
      "x": "0.745148463",
      "y": "0.526619236"
    },
    {
      "turn": "0",
      "x": "0.991181600",
      "y": "0.427189714"
    },
    {
      "turn": "0",
      "x": "0.526286106",
      "y": "0.676678568"
    },
    {
      "turn": "0",
      "x": "1.255723708",
      "y": "0.390682676"
    },
    {
      "turn": "0",
      "x": "1.519148501",
      "y": "0.358652804"
    },
    {
      "turn": "0",
      "x": "0.161176095",
      "y": "0.957602447"
    },
    {
      "turn": "0",
      "x": "0.424178294",
      "y": "0.922270053"
    },
    {
      "turn": "0",
      "x": "0.906135326",
      "y": "0.737573649"
    },
    {
      "turn": "0",
      "x": "1.152168463",
      "y": "0.638144127"
    },
    {
      "turn": "0",
      "x": "0.687272969",
      "y": "0.887632982"
    },
    {
      "turn": "0",
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    },
    {
      "turn": "0",
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    },
    {
      "turn": "0",
      "x": "0.322720016",
      "y": "1.168130583"
    },
    {
      "turn": "0",
      "x": "0.585722215",
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    },
    {
      "turn": "0",
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      "y": "0.948101786"
    },
    {
      "turn": "0",
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    },
    {
      "turn": "0",
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    },
    {
      "turn": "0",
      "x": "1.577051145",
      "y": "0.815942594"
    },
    {
      "turn": "0",
      "x": "0.323174004",
      "y": "1.433495103"
    },
    {
      "turn": "0",
      "x": "0.587175464",
      "y": "1.398159118"
    },
    {
      "turn": "0",
      "x": "1.273953774",
      "y": "1.115042954"
    },
    {
      "turn": "0",
      "x": "1.822213262",
      "y": "0.917500808"
    },
    {
      "turn": "0",
      "x": "1.536752796",
      "y": "1.078229798"
    },
    {
      "turn": "0",
      "x": "0.850270139",
      "y": "1.363522047"
    },
    {
      "turn": "0",
      "x": "1.113327574",
      "y": "1.328582796"
    },
    {
      "turn": "0",
      "x": "0.485624710",
      "y": "1.643324325"
    },
    {
      "turn": "0",
      "x": "1.781914913",
      "y": "1.179788012"
    },
    {
      "turn": "0",
      "x": "0.748719385",
      "y": "1.608687254"
    },
    {
      "turn": "0",
      "x": "1.433791445",
      "y": "1.326869425"
    },
    {
      "turn": "0",
      "x": "1.011814060",
      "y": "1.574050183"
    },
    {
      "turn": "0",
      "x": "1.274908735",
      "y": "1.539413112"
    },
    {
      "turn": "0",
      "x": "1.680364159",
      "y": "1.424953220"
    },
    {
      "turn": "0",
      "x": "0.910263306",
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    },
    {
      "turn": "0",
      "x": "1.520322016",
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    },
    {
      "turn": "0",
      "x": "1.173357981",
      "y": "1.784578320"
    }
  ],
  "radius": "0.132682453"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 40,
  "sides": 8
}

Starter answer

{
  "placements": [
    {
      "turn": "0",
      "x": "0.583604542",
      "y": "0.316091100"
    },
    {
      "turn": "0",
      "x": "0.828769749",
      "y": "0.214540346"
    },
    {
      "turn": "0",
      "x": "0.364742185",
      "y": "0.466150432"
    },
    {
      "turn": "0",
      "x": "1.092102790",
      "y": "0.181764678"
    },
    {
      "turn": "0",
      "x": "0.263191431",
      "y": "0.711315639"
    },
    {
      "turn": "0",
      "x": "0.745148463",
      "y": "0.526619236"
    },
    {
      "turn": "0",
      "x": "0.991181600",
      "y": "0.427189714"
    },
    {
      "turn": "0",
      "x": "0.526286106",
      "y": "0.676678568"
    },
    {
      "turn": "0",
      "x": "1.255723708",
      "y": "0.390682676"
    },
    {
      "turn": "0",
      "x": "1.519148501",
      "y": "0.358652804"
    },
    {
      "turn": "0",
      "x": "0.161176095",
      "y": "0.957602447"
    },
    {
      "turn": "0",
      "x": "0.424178294",
      "y": "0.922270053"
    },
    {
      "turn": "0",
      "x": "0.906135326",
      "y": "0.737573649"
    },
    {
      "turn": "0",
      "x": "1.152168463",
      "y": "0.638144127"
    },
    {
      "turn": "0",
      "x": "0.687272969",
      "y": "0.887632982"
    },
    {
      "turn": "0",
      "x": "1.415169645",
      "y": "0.602804168"
    },
    {
      "turn": "0",
      "x": "1.678594439",
      "y": "0.570774296"
    },
    {
      "turn": "0",
      "x": "0.322720016",
      "y": "1.168130583"
    },
    {
      "turn": "0",
      "x": "0.585722215",
      "y": "1.132798189"
    },
    {
      "turn": "0",
      "x": "1.067679246",
      "y": "0.948101786"
    },
    {
      "turn": "0",
      "x": "1.313712384",
      "y": "0.848672263"
    },
    {
      "turn": "0",
      "x": "0.848816889",
      "y": "1.098161118"
    },
    {
      "turn": "0",
      "x": "1.577051145",
      "y": "0.815942594"
    },
    {
      "turn": "0",
      "x": "0.323174004",
      "y": "1.433495103"
    },
    {
      "turn": "0",
      "x": "0.587175464",
      "y": "1.398159118"
    },
    {
      "turn": "0",
      "x": "1.273953774",
      "y": "1.115042954"
    },
    {
      "turn": "0",
      "x": "1.822213262",
      "y": "0.917500808"
    },
    {
      "turn": "0",
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      "y": "1.078229798"
    },
    {
      "turn": "0",
      "x": "0.850270139",
      "y": "1.363522047"
    },
    {
      "turn": "0",
      "x": "1.113327574",
      "y": "1.328582796"
    },
    {
      "turn": "0",
      "x": "0.485624710",
      "y": "1.643324325"
    },
    {
      "turn": "0",
      "x": "1.781914913",
      "y": "1.179788012"
    },
    {
      "turn": "0",
      "x": "0.748719385",
      "y": "1.608687254"
    },
    {
      "turn": "0",
      "x": "1.433791445",
      "y": "1.326869425"
    },
    {
      "turn": "0",
      "x": "1.011814060",
      "y": "1.574050183"
    },
    {
      "turn": "0",
      "x": "1.274908735",
      "y": "1.539413112"
    },
    {
      "turn": "0",
      "x": "1.680364159",
      "y": "1.424953220"
    },
    {
      "turn": "0",
      "x": "0.910263306",
      "y": "1.819215391"
    },
    {
      "turn": "0",
      "x": "1.520322016",
      "y": "1.640797055"
    },
    {
      "turn": "0",
      "x": "1.173357981",
      "y": "1.784578320"
    }
  ],
  "radius": "0.132682453"
}

Submit {radius, placements:[{x,y,turn},…]}, with each value written as a decimal string of at most nine places. Here x, y are centre coordinates; circles require turn = 0 and polygons use turn = tan(θ/2). Coordinates and turn must lie in [−4, 4], with 0 < radius ≤ 4. · Verifier v1.0.0

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