P82 · Packing and covering · Classic · Hard

Equal circles in regular polygons · m = 5 · n = 28

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 = 5 · n = 28
ObjectiveMaximize circle radius

Record comparison

circle radius · Higher is better
RecordValue / intervalAuthor / holderSource
External best known[0.145444423783, 0.145444423785]Eckard SpechtPackomania ↗
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 = 5 · n = 28
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": "0.336427429",
      "y": "1.245434422"
    },
    {
      "turn": "0",
      "x": "0.336427429",
      "y": "0.785304383"
    },
    {
      "turn": "0",
      "x": "0.392108523",
      "y": "0.499794423"
    },
    {
      "turn": "0",
      "x": "0.442102169",
      "y": "1.516449497"
    },
    {
      "turn": "0",
      "x": "0.514434195",
      "y": "1.015369403"
    },
    {
      "turn": "0",
      "x": "0.624672963",
      "y": "1.284560293"
    },
    {
      "turn": "0",
      "x": "0.624672963",
      "y": "0.746178512"
    },
    {
      "turn": "0",
      "x": "0.668760257",
      "y": "0.409904826"
    },
    {
      "turn": "0",
      "x": "0.718753903",
      "y": "1.606339095"
    },
    {
      "turn": "0",
      "x": "0.804761146",
      "y": "0.997297786"
    },
    {
      "turn": "0",
      "x": "0.881059229",
      "y": "0.608765250"
    },
    {
      "turn": "0",
      "x": "0.899895750",
      "y": "1.378734277"
    },
    {
      "turn": "0",
      "x": "0.945411991",
      "y": "0.320015228"
    },
    {
      "turn": "0",
      "x": "0.995405637",
      "y": "1.696228692"
    },
    {
      "turn": "0",
      "x": "1.052039403",
      "y": "0.844099271"
    },
    {
      "turn": "0",
      "x": "1.060384886",
      "y": "1.136124387"
    },
    {
      "turn": "0",
      "x": "1.157710963",
      "y": "0.518875653"
    },
    {
      "turn": "0",
      "x": "1.176547484",
      "y": "1.468623875"
    },
    {
      "turn": "0",
      "x": "1.251591096",
      "y": "0.225608769"
    },
    {
      "turn": "0",
      "x": "1.283088114",
      "y": "1.739299725"
    },
    {
      "turn": "0",
      "x": "1.328691137",
      "y": "0.754209674"
    },
    {
      "turn": "0",
      "x": "1.337036620",
      "y": "1.226013984"
    },
    {
      "turn": "0",
      "x": "1.446728288",
      "y": "0.485931652"
    },
    {
      "turn": "0",
      "x": "1.466898380",
      "y": "1.486306598"
    },
    {
      "turn": "0",
      "x": "1.508016794",
      "y": "0.990679963"
    },
    {
      "turn": "0",
      "x": "1.617708463",
      "y": "0.721265673"
    },
    {
      "turn": "0",
      "x": "1.637878555",
      "y": "1.250972577"
    },
    {
      "turn": "0",
      "x": "1.814411182",
      "y": "0.999975974"
    }
  ],
  "radius": "0.145444423"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 28,
  "sides": 5
}

Starter answer

{
  "placements": [
    {
      "turn": "0",
      "x": "0.336427429",
      "y": "1.245434422"
    },
    {
      "turn": "0",
      "x": "0.336427429",
      "y": "0.785304383"
    },
    {
      "turn": "0",
      "x": "0.392108523",
      "y": "0.499794423"
    },
    {
      "turn": "0",
      "x": "0.442102169",
      "y": "1.516449497"
    },
    {
      "turn": "0",
      "x": "0.514434195",
      "y": "1.015369403"
    },
    {
      "turn": "0",
      "x": "0.624672963",
      "y": "1.284560293"
    },
    {
      "turn": "0",
      "x": "0.624672963",
      "y": "0.746178512"
    },
    {
      "turn": "0",
      "x": "0.668760257",
      "y": "0.409904826"
    },
    {
      "turn": "0",
      "x": "0.718753903",
      "y": "1.606339095"
    },
    {
      "turn": "0",
      "x": "0.804761146",
      "y": "0.997297786"
    },
    {
      "turn": "0",
      "x": "0.881059229",
      "y": "0.608765250"
    },
    {
      "turn": "0",
      "x": "0.899895750",
      "y": "1.378734277"
    },
    {
      "turn": "0",
      "x": "0.945411991",
      "y": "0.320015228"
    },
    {
      "turn": "0",
      "x": "0.995405637",
      "y": "1.696228692"
    },
    {
      "turn": "0",
      "x": "1.052039403",
      "y": "0.844099271"
    },
    {
      "turn": "0",
      "x": "1.060384886",
      "y": "1.136124387"
    },
    {
      "turn": "0",
      "x": "1.157710963",
      "y": "0.518875653"
    },
    {
      "turn": "0",
      "x": "1.176547484",
      "y": "1.468623875"
    },
    {
      "turn": "0",
      "x": "1.251591096",
      "y": "0.225608769"
    },
    {
      "turn": "0",
      "x": "1.283088114",
      "y": "1.739299725"
    },
    {
      "turn": "0",
      "x": "1.328691137",
      "y": "0.754209674"
    },
    {
      "turn": "0",
      "x": "1.337036620",
      "y": "1.226013984"
    },
    {
      "turn": "0",
      "x": "1.446728288",
      "y": "0.485931652"
    },
    {
      "turn": "0",
      "x": "1.466898380",
      "y": "1.486306598"
    },
    {
      "turn": "0",
      "x": "1.508016794",
      "y": "0.990679963"
    },
    {
      "turn": "0",
      "x": "1.617708463",
      "y": "0.721265673"
    },
    {
      "turn": "0",
      "x": "1.637878555",
      "y": "1.250972577"
    },
    {
      "turn": "0",
      "x": "1.814411182",
      "y": "0.999975974"
    }
  ],
  "radius": "0.145444423"
}

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

DISCUSSION

Discussion

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