P82 · Packing and covering · Classic · Hard

Equal circles in regular polygons · m = 5 · n = 20

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 = 20
ObjectiveMaximize circle radius

Record comparison

circle radius · Higher is better
RecordValue / intervalAuthor / holderSource
External best known[0.169279411748, 0.16927941175]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 = 20
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": "0.360262417",
      "y": "1.450934997"
    },
    {
      "turn": "0",
      "x": "0.360262417",
      "y": "1.112376173"
    },
    {
      "turn": "0",
      "x": "0.360262417",
      "y": "0.768738997"
    },
    {
      "turn": "0",
      "x": "0.534643391",
      "y": "0.478543627"
    },
    {
      "turn": "0",
      "x": "0.651982231",
      "y": "0.940557585"
    },
    {
      "turn": "0",
      "x": "0.677932982",
      "y": "1.568013984"
    },
    {
      "turn": "0",
      "x": "0.791452521",
      "y": "1.249054125"
    },
    {
      "turn": "0",
      "x": "0.826363204",
      "y": "0.650362215"
    },
    {
      "turn": "0",
      "x": "0.961377059",
      "y": "0.339889453"
    },
    {
      "turn": "0",
      "x": "0.990489281",
      "y": "0.946478253"
    },
    {
      "turn": "0",
      "x": "1.010920092",
      "y": "1.506844859"
    },
    {
      "turn": "0",
      "x": "1.164888258",
      "y": "0.655143982"
    },
    {
      "turn": "0",
      "x": "1.190354963",
      "y": "1.219746959"
    },
    {
      "turn": "0",
      "x": "1.244358013",
      "y": "1.752056633"
    },
    {
      "turn": "0",
      "x": "1.299559096",
      "y": "0.323921140"
    },
    {
      "turn": "0",
      "x": "1.363888141",
      "y": "0.929043824"
    },
    {
      "turn": "0",
      "x": "1.423792884",
      "y": "1.464958733"
    },
    {
      "turn": "0",
      "x": "1.498558980",
      "y": "0.597820982"
    },
    {
      "turn": "0",
      "x": "1.641390788",
      "y": "1.205587900"
    },
    {
      "turn": "0",
      "x": "1.697558863",
      "y": "0.871720824"
    }
  ],
  "radius": "0.169279411"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 20,
  "sides": 5
}

Starter answer

{
  "placements": [
    {
      "turn": "0",
      "x": "0.360262417",
      "y": "1.450934997"
    },
    {
      "turn": "0",
      "x": "0.360262417",
      "y": "1.112376173"
    },
    {
      "turn": "0",
      "x": "0.360262417",
      "y": "0.768738997"
    },
    {
      "turn": "0",
      "x": "0.534643391",
      "y": "0.478543627"
    },
    {
      "turn": "0",
      "x": "0.651982231",
      "y": "0.940557585"
    },
    {
      "turn": "0",
      "x": "0.677932982",
      "y": "1.568013984"
    },
    {
      "turn": "0",
      "x": "0.791452521",
      "y": "1.249054125"
    },
    {
      "turn": "0",
      "x": "0.826363204",
      "y": "0.650362215"
    },
    {
      "turn": "0",
      "x": "0.961377059",
      "y": "0.339889453"
    },
    {
      "turn": "0",
      "x": "0.990489281",
      "y": "0.946478253"
    },
    {
      "turn": "0",
      "x": "1.010920092",
      "y": "1.506844859"
    },
    {
      "turn": "0",
      "x": "1.164888258",
      "y": "0.655143982"
    },
    {
      "turn": "0",
      "x": "1.190354963",
      "y": "1.219746959"
    },
    {
      "turn": "0",
      "x": "1.244358013",
      "y": "1.752056633"
    },
    {
      "turn": "0",
      "x": "1.299559096",
      "y": "0.323921140"
    },
    {
      "turn": "0",
      "x": "1.363888141",
      "y": "0.929043824"
    },
    {
      "turn": "0",
      "x": "1.423792884",
      "y": "1.464958733"
    },
    {
      "turn": "0",
      "x": "1.498558980",
      "y": "0.597820982"
    },
    {
      "turn": "0",
      "x": "1.641390788",
      "y": "1.205587900"
    },
    {
      "turn": "0",
      "x": "1.697558863",
      "y": "0.871720824"
    }
  ],
  "radius": "0.169279411"
}

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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