P82 · Packing and covering · Classic · Hard

Equal circles in regular polygons · m = 5 · n = 26

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 = 26
ObjectiveMaximize circle radius

Record comparison

circle radius · Higher is better
RecordValue / intervalAuthor / holderSource
External best known[0.150683336699, 0.150683336701]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 = 5 · n = 26
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": "0.341666342",
      "y": "1.478307400"
    },
    {
      "turn": "0",
      "x": "0.341666342",
      "y": "1.176940727"
    },
    {
      "turn": "0",
      "x": "0.341666342",
      "y": "0.875574053"
    },
    {
      "turn": "0",
      "x": "0.341666342",
      "y": "0.574207380"
    },
    {
      "turn": "0",
      "x": "0.608885955",
      "y": "0.736234358"
    },
    {
      "turn": "0",
      "x": "0.608885955",
      "y": "0.434867685"
    },
    {
      "turn": "0",
      "x": "0.628283081",
      "y": "1.571434824"
    },
    {
      "turn": "0",
      "x": "0.628283081",
      "y": "1.270068150"
    },
    {
      "turn": "0",
      "x": "0.758074629",
      "y": "0.998082809"
    },
    {
      "turn": "0",
      "x": "0.895502693",
      "y": "0.341740261"
    },
    {
      "turn": "0",
      "x": "0.910247702",
      "y": "0.737957401"
    },
    {
      "turn": "0",
      "x": "0.914899819",
      "y": "1.664562247"
    },
    {
      "turn": "0",
      "x": "0.928725070",
      "y": "1.246478258"
    },
    {
      "turn": "0",
      "x": "1.080898143",
      "y": "0.986352850"
    },
    {
      "turn": "0",
      "x": "1.129699490",
      "y": "0.531407686"
    },
    {
      "turn": "0",
      "x": "1.138662879",
      "y": "1.462691088"
    },
    {
      "turn": "0",
      "x": "1.218666337",
      "y": "0.237841012"
    },
    {
      "turn": "0",
      "x": "1.251279600",
      "y": "1.772382729"
    },
    {
      "turn": "0",
      "x": "1.291878833",
      "y": "1.202303636"
    },
    {
      "turn": "0",
      "x": "1.300349931",
      "y": "0.779803135"
    },
    {
      "turn": "0",
      "x": "1.423012530",
      "y": "0.462202682"
    },
    {
      "turn": "0",
      "x": "1.433999680",
      "y": "1.522674803"
    },
    {
      "turn": "0",
      "x": "1.512108788",
      "y": "0.994232747"
    },
    {
      "turn": "0",
      "x": "1.600151416",
      "y": "0.706013442"
    },
    {
      "turn": "0",
      "x": "1.611138566",
      "y": "1.278864043"
    },
    {
      "turn": "0",
      "x": "1.813571160",
      "y": "1.000001673"
    }
  ],
  "radius": "0.150683336"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 26,
  "sides": 5
}

Starter answer

{
  "placements": [
    {
      "turn": "0",
      "x": "0.341666342",
      "y": "1.478307400"
    },
    {
      "turn": "0",
      "x": "0.341666342",
      "y": "1.176940727"
    },
    {
      "turn": "0",
      "x": "0.341666342",
      "y": "0.875574053"
    },
    {
      "turn": "0",
      "x": "0.341666342",
      "y": "0.574207380"
    },
    {
      "turn": "0",
      "x": "0.608885955",
      "y": "0.736234358"
    },
    {
      "turn": "0",
      "x": "0.608885955",
      "y": "0.434867685"
    },
    {
      "turn": "0",
      "x": "0.628283081",
      "y": "1.571434824"
    },
    {
      "turn": "0",
      "x": "0.628283081",
      "y": "1.270068150"
    },
    {
      "turn": "0",
      "x": "0.758074629",
      "y": "0.998082809"
    },
    {
      "turn": "0",
      "x": "0.895502693",
      "y": "0.341740261"
    },
    {
      "turn": "0",
      "x": "0.910247702",
      "y": "0.737957401"
    },
    {
      "turn": "0",
      "x": "0.914899819",
      "y": "1.664562247"
    },
    {
      "turn": "0",
      "x": "0.928725070",
      "y": "1.246478258"
    },
    {
      "turn": "0",
      "x": "1.080898143",
      "y": "0.986352850"
    },
    {
      "turn": "0",
      "x": "1.129699490",
      "y": "0.531407686"
    },
    {
      "turn": "0",
      "x": "1.138662879",
      "y": "1.462691088"
    },
    {
      "turn": "0",
      "x": "1.218666337",
      "y": "0.237841012"
    },
    {
      "turn": "0",
      "x": "1.251279600",
      "y": "1.772382729"
    },
    {
      "turn": "0",
      "x": "1.291878833",
      "y": "1.202303636"
    },
    {
      "turn": "0",
      "x": "1.300349931",
      "y": "0.779803135"
    },
    {
      "turn": "0",
      "x": "1.423012530",
      "y": "0.462202682"
    },
    {
      "turn": "0",
      "x": "1.433999680",
      "y": "1.522674803"
    },
    {
      "turn": "0",
      "x": "1.512108788",
      "y": "0.994232747"
    },
    {
      "turn": "0",
      "x": "1.600151416",
      "y": "0.706013442"
    },
    {
      "turn": "0",
      "x": "1.611138566",
      "y": "1.278864043"
    },
    {
      "turn": "0",
      "x": "1.813571160",
      "y": "1.000001673"
    }
  ],
  "radius": "0.150683336"
}

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

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