P84 · Packing and covering · Classic · Hard

Equilateral triangles in a disc · n = 33

Pack n unit-side equilateral triangles into a disc. Contact is allowed; interiors cannot overlap. Minimise the container circle radius.

Instancen = 33
ObjectiveMinimize container circle radius

Record comparison

container circle radius · Lower is better
RecordValue / intervalAuthor / holderSource
External best known[2.34169, 2.3417)Thomas SchadtErich Friedman ↗
Site record2.341693793NUE_13Record details ↓

Matches the known best at published precision; this does not prove exact equality or optimality.

Formal definition

  • ContainerThe editor and certificate normalise the container to the closed unit disc centred at (1,1), while public scores are reported in the literature's unit-piece scale. 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.
  • ObjectiveContainer circle radius = 1/(2 sin(π/3) r), where smaller is better. Pages, leaderboards, and literature records share this unit with automatic conversion.
Open full editor ↗

Layout shown: site record

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.

Source
The record-holding arrangement for Equilateral triangles in a disc n = 33, 2.341693793
LAYOUT & HISTORY

Record details

Inspect the layout, solver notes and record history.

Record holderNUE_13
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
Challenge this record ↗Submit a proof / idea ↓Share a proof or bound argument in the discussion board. Accepted contributions earn proof points.
Record holder's solver noteNo solver note yet (expand)+

The record holder has not shared a solver note yet.

Record history (1 changes)
  1. NUE_13AI · DeepSeek: DeepSeek V4.1 Flash
    2.341693803→2.341693793
ANSWER FORMAT

How to write your answer

the closed unit disc centred at (1,1)

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.

The current leader's answer

{
  "placements": [
    {
      "turn": "0.172925527",
      "x": "1.209984722",
      "y": "1.814112101"
    },
    {
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      "y": "1.731317513"
    },
    {
      "turn": "0.183515780",
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    },
    {
      "turn": "0.172925527",
      "x": "1.506187025",
      "y": "1.591544149"
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    {
      "turn": "-0.356104219",
      "x": "0.338478455",
      "y": "1.539563374"
    },
    {
      "turn": "-0.367712810",
      "x": "1.273951903",
      "y": "1.508749561"
    },
    {
      "turn": "0.172925527",
      "x": "0.933334255",
      "y": "1.488798704"
    },
    {
      "turn": "-0.367712810",
      "x": "1.694006803",
      "y": "1.431819928"
    },
    {
      "turn": "-0.367712810",
      "x": "0.703818928",
      "y": "1.398375212"
    },
    {
      "turn": "0.172925527",
      "x": "1.255569156",
      "y": "1.261463094"
    },
    {
      "turn": "0.172925527",
      "x": "0.497383399",
      "y": "1.185529080"
    },
    {
      "turn": "0.172925527",
      "x": "1.675624055",
      "y": "1.184533460"
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    {
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    {
      "turn": "-0.367712810",
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    },
    {
      "turn": "-0.367712810",
      "x": "1.443388933",
      "y": "1.101738872"
    },
    {
      "turn": "-0.367712810",
      "x": "0.685203176",
      "y": "1.025804859"
    },
    {
      "turn": "0.172925527",
      "x": "0.192691986",
      "y": "0.938869284"
    },
    {
      "turn": "0.172925527",
      "x": "0.978918689",
      "y": "0.936149696"
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    {
      "turn": "-0.367712810",
      "x": "1.786428684",
      "y": "0.934247094"
    },
    {
      "turn": "0.172925527",
      "x": "1.398973589",
      "y": "0.859220063"
    },
    {
      "turn": "0.172925527",
      "x": "0.640787832",
      "y": "0.783286050"
    },
    {
      "turn": "-0.367712810",
      "x": "0.380511764",
      "y": "0.779145063"
    },
    {
      "turn": "-0.367712810",
      "x": "1.166738467",
      "y": "0.776425475"
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    {
      "turn": "0.172925527",
      "x": "1.742013340",
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    {
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      "x": "0.828607609",
      "y": "0.623561828"
    },
    {
      "turn": "-0.367712810",
      "x": "1.509778218",
      "y": "0.608933697"
    },
    {
      "turn": "0.172925527",
      "x": "0.336096419",
      "y": "0.536626254"
    },
    {
      "turn": "0.172925527",
      "x": "1.122323122",
      "y": "0.533906666"
    },
    {
      "turn": "0.172925527",
      "x": "0.784192265",
      "y": "0.381043019"
    },
    {
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      "x": "0.523916197",
      "y": "0.376902032"
    },
    {
      "turn": "0.172925527",
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    },
    {
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      "x": "1.278785359",
      "y": "0.275258480"
    },
    {
      "turn": "-0.367712810",
      "x": "0.925067245",
      "y": "0.166116391"
    }
  ],
  "radius": "0.246552419"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 33,
  "sides": 5
}

The current leader's answer

{
  "placements": [
    {
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      "x": "1.209984722",
      "y": "1.814112101"
    },
    {
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      "x": "0.977749600",
      "y": "1.731317513"
    },
    {
      "turn": "0.183515780",
      "x": "0.568965132",
      "y": "1.627107576"
    },
    {
      "turn": "0.172925527",
      "x": "1.506187025",
      "y": "1.591544149"
    },
    {
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      "x": "0.338478455",
      "y": "1.539563374"
    },
    {
      "turn": "-0.367712810",
      "x": "1.273951903",
      "y": "1.508749561"
    },
    {
      "turn": "0.172925527",
      "x": "0.933334255",
      "y": "1.488798704"
    },
    {
      "turn": "-0.367712810",
      "x": "1.694006803",
      "y": "1.431819928"
    },
    {
      "turn": "-0.367712810",
      "x": "0.703818928",
      "y": "1.398375212"
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    {
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      "x": "1.255569156",
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      "y": "1.185529080"
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    {
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      "y": "1.181388094"
    },
    {
      "turn": "-0.367712810",
      "x": "1.023334034",
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    {
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    {
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      "x": "1.122323122",
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    {
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      "x": "0.784192265",
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    {
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    {
      "turn": "0.172925527",
      "x": "1.511020481",
      "y": "0.358053068"
    },
    {
      "turn": "-0.367712810",
      "x": "1.278785359",
      "y": "0.275258480"
    },
    {
      "turn": "-0.367712810",
      "x": "0.925067245",
      "y": "0.166116391"
    }
  ],
  "radius": "0.246552419"
}

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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