P84 · Packing and covering · Classic · Hard

Equilateral triangles in a disc · n = 32

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

Instancen = 32
ObjectiveMinimize container circle radius

Record comparison

container circle radius · Lower is better
RecordValue / intervalAuthor / holderSource
External best known[2.31295, 2.31296)Thomas SchadtErich Friedman ↗
Site recordNo player record yet——

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: 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.

Source
The current arrangement for Equilateral triangles in a disc n = 32
LAYOUT & HISTORY

Starter layout

Inspect the layout, solver notes and record history.

Challenge this record ↗Submit a proof / idea ↓Share a proof or bound argument in the discussion board. Accepted contributions earn proof points.
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.

Starter answer

{
  "placements": [
    {
      "turn": "0.577232428",
      "x": "0.997305461",
      "y": "1.776359860"
    },
    {
      "turn": "-0.000088385",
      "x": "1.246921299",
      "y": "1.776315736"
    },
    {
      "turn": "0.535854130",
      "x": "0.621776579",
      "y": "1.762941251"
    },
    {
      "turn": "-0.000088385",
      "x": "0.872459329",
      "y": "1.560208266"
    },
    {
      "turn": "-0.000088385",
      "x": "1.590572587",
      "y": "1.542338704"
    },
    {
      "turn": "0.577232428",
      "x": "1.340956749",
      "y": "1.542382828"
    },
    {
      "turn": "-0.165644408",
      "x": "0.421100098",
      "y": "1.533875848"
    },
    {
      "turn": "-0.000088385",
      "x": "1.216110617",
      "y": "1.326231234"
    },
    {
      "turn": "0.577232428",
      "x": "0.966494779",
      "y": "1.326275359"
    },
    {
      "turn": "0.577232428",
      "x": "1.715342293",
      "y": "1.326142984"
    },
    {
      "turn": "0.375769230",
      "x": "0.349979002",
      "y": "1.265354556"
    },
    {
      "turn": "-0.000088385",
      "x": "0.662593946",
      "y": "1.213543250"
    },
    {
      "turn": "-0.577468122",
      "x": "1.340880323",
      "y": "1.110035514"
    },
    {
      "turn": "-0.000088385",
      "x": "1.590496161",
      "y": "1.109991390"
    },
    {
      "turn": "-0.017019833",
      "x": "0.148946192",
      "y": "1.028977981"
    },
    {
      "turn": "-0.000088385",
      "x": "1.036979490",
      "y": "0.997303406"
    },
    {
      "turn": "0.577232428",
      "x": "0.787363652",
      "y": "0.997347531"
    },
    {
      "turn": "-0.577468122",
      "x": "1.843956888",
      "y": "0.968065138"
    },
    {
      "turn": "0.577232428",
      "x": "0.412919979",
      "y": "0.884752148"
    },
    {
      "turn": "-0.000088385",
      "x": "0.662517520",
      "y": "0.781195936"
    },
    {
      "turn": "0.577232428",
      "x": "1.161749196",
      "y": "0.781107687"
    },
    {
      "turn": "-0.000088385",
      "x": "1.411365034",
      "y": "0.781063562"
    },
    {
      "turn": "-0.000088385",
      "x": "0.288073847",
      "y": "0.668600553"
    },
    {
      "turn": "-0.577468122",
      "x": "1.683996049",
      "y": "0.628064821"
    },
    {
      "turn": "-0.000088385",
      "x": "1.036903064",
      "y": "0.564956092"
    },
    {
      "turn": "-0.577468122",
      "x": "0.787287225",
      "y": "0.565000217"
    },
    {
      "turn": "-0.577468122",
      "x": "0.412843553",
      "y": "0.452404834"
    },
    {
      "turn": "0.577232428",
      "x": "1.309537992",
      "y": "0.434095551"
    },
    {
      "turn": "-0.000088385",
      "x": "1.559149917",
      "y": "0.411913226"
    },
    {
      "turn": "-0.000088385",
      "x": "0.662441093",
      "y": "0.348848622"
    },
    {
      "turn": "-0.577468122",
      "x": "0.935076022",
      "y": "0.217988081"
    },
    {
      "turn": "-0.000088385",
      "x": "1.184691860",
      "y": "0.217943956"
    }
  ],
  "radius": "0.249615841"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 32,
  "sides": 5
}

Starter answer

{
  "placements": [
    {
      "turn": "0.577232428",
      "x": "0.997305461",
      "y": "1.776359860"
    },
    {
      "turn": "-0.000088385",
      "x": "1.246921299",
      "y": "1.776315736"
    },
    {
      "turn": "0.535854130",
      "x": "0.621776579",
      "y": "1.762941251"
    },
    {
      "turn": "-0.000088385",
      "x": "0.872459329",
      "y": "1.560208266"
    },
    {
      "turn": "-0.000088385",
      "x": "1.590572587",
      "y": "1.542338704"
    },
    {
      "turn": "0.577232428",
      "x": "1.340956749",
      "y": "1.542382828"
    },
    {
      "turn": "-0.165644408",
      "x": "0.421100098",
      "y": "1.533875848"
    },
    {
      "turn": "-0.000088385",
      "x": "1.216110617",
      "y": "1.326231234"
    },
    {
      "turn": "0.577232428",
      "x": "0.966494779",
      "y": "1.326275359"
    },
    {
      "turn": "0.577232428",
      "x": "1.715342293",
      "y": "1.326142984"
    },
    {
      "turn": "0.375769230",
      "x": "0.349979002",
      "y": "1.265354556"
    },
    {
      "turn": "-0.000088385",
      "x": "0.662593946",
      "y": "1.213543250"
    },
    {
      "turn": "-0.577468122",
      "x": "1.340880323",
      "y": "1.110035514"
    },
    {
      "turn": "-0.000088385",
      "x": "1.590496161",
      "y": "1.109991390"
    },
    {
      "turn": "-0.017019833",
      "x": "0.148946192",
      "y": "1.028977981"
    },
    {
      "turn": "-0.000088385",
      "x": "1.036979490",
      "y": "0.997303406"
    },
    {
      "turn": "0.577232428",
      "x": "0.787363652",
      "y": "0.997347531"
    },
    {
      "turn": "-0.577468122",
      "x": "1.843956888",
      "y": "0.968065138"
    },
    {
      "turn": "0.577232428",
      "x": "0.412919979",
      "y": "0.884752148"
    },
    {
      "turn": "-0.000088385",
      "x": "0.662517520",
      "y": "0.781195936"
    },
    {
      "turn": "0.577232428",
      "x": "1.161749196",
      "y": "0.781107687"
    },
    {
      "turn": "-0.000088385",
      "x": "1.411365034",
      "y": "0.781063562"
    },
    {
      "turn": "-0.000088385",
      "x": "0.288073847",
      "y": "0.668600553"
    },
    {
      "turn": "-0.577468122",
      "x": "1.683996049",
      "y": "0.628064821"
    },
    {
      "turn": "-0.000088385",
      "x": "1.036903064",
      "y": "0.564956092"
    },
    {
      "turn": "-0.577468122",
      "x": "0.787287225",
      "y": "0.565000217"
    },
    {
      "turn": "-0.577468122",
      "x": "0.412843553",
      "y": "0.452404834"
    },
    {
      "turn": "0.577232428",
      "x": "1.309537992",
      "y": "0.434095551"
    },
    {
      "turn": "-0.000088385",
      "x": "1.559149917",
      "y": "0.411913226"
    },
    {
      "turn": "-0.000088385",
      "x": "0.662441093",
      "y": "0.348848622"
    },
    {
      "turn": "-0.577468122",
      "x": "0.935076022",
      "y": "0.217988081"
    },
    {
      "turn": "-0.000088385",
      "x": "1.184691860",
      "y": "0.217943956"
    }
  ],
  "radius": "0.249615841"
}

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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