P83 · Packing and covering · Classic · Hard

Equilateral triangles in a square · n = 31

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

Instancen = 31
ObjectiveMinimize container square side

Record comparison

container square side · Lower is better
RecordValue / intervalAuthor / holderSource
External best known[3.93107, 3.93108)31. Found by Jake LoydErich Friedman ↗
Site recordNo player record yet——

Formal definition

  • ContainerThe editor and certificate normalise the container to the unit square [0,1]², 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 square side = 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 square n = 31
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 unit square [0,1]²

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": "0.267949192",
      "x": "0.140296767",
      "y": "0.926565912"
    },
    {
      "turn": "0.267949192",
      "x": "0.394679909",
      "y": "0.926565912"
    },
    {
      "turn": "0.267949192",
      "x": "0.649063051",
      "y": "0.926565912"
    },
    {
      "turn": "-0.267949192",
      "x": "0.267488338",
      "y": "0.853131825"
    },
    {
      "turn": "-0.577350269",
      "x": "0.926565912",
      "y": "0.872808429"
    },
    {
      "turn": "-0.267949192",
      "x": "0.521871480",
      "y": "0.853131825"
    },
    {
      "turn": "0.000000000",
      "x": "0.853131825",
      "y": "0.745616858"
    },
    {
      "turn": "0.000000000",
      "x": "0.073434088",
      "y": "0.733506542"
    },
    {
      "turn": "-0.577350269",
      "x": "0.706263649",
      "y": "0.727928137"
    },
    {
      "turn": "0.267949192",
      "x": "0.335695605",
      "y": "0.706263649"
    },
    {
      "turn": "0.577350269",
      "x": "0.926565912",
      "y": "0.618425287"
    },
    {
      "turn": "-0.577350269",
      "x": "0.158020878",
      "y": "0.612753987"
    },
    {
      "turn": "0.000000000",
      "x": "0.632829561",
      "y": "0.600736566"
    },
    {
      "turn": "-0.552464823",
      "x": "0.482459254",
      "y": "0.564935541"
    },
    {
      "turn": "-0.000000000",
      "x": "0.304889053",
      "y": "0.492387264"
    },
    {
      "turn": "0.000000000",
      "x": "0.853131825",
      "y": "0.491233716"
    },
    {
      "turn": "0.000000000",
      "x": "0.084586790",
      "y": "0.485562416"
    },
    {
      "turn": "0.577350269",
      "x": "0.706263649",
      "y": "0.473544995"
    },
    {
      "turn": "-0.577350269",
      "x": "0.926565912",
      "y": "0.364042145"
    },
    {
      "turn": "0.577350269",
      "x": "0.158020878",
      "y": "0.358370845"
    },
    {
      "turn": "0.267949192",
      "x": "0.489258467",
      "y": "0.367170439"
    },
    {
      "turn": "-0.267949192",
      "x": "0.362066896",
      "y": "0.293736351"
    },
    {
      "turn": "-0.267949192",
      "x": "0.616450038",
      "y": "0.293736351"
    },
    {
      "turn": "-0.000000000",
      "x": "0.073434088",
      "y": "0.237618290"
    },
    {
      "turn": "0.054686686",
      "x": "0.826267880",
      "y": "0.236850574"
    },
    {
      "turn": "-0.506666415",
      "x": "0.913133940",
      "y": "0.118425287"
    },
    {
      "turn": "0.267949192",
      "x": "0.317501596",
      "y": "0.146868175"
    },
    {
      "turn": "0.267949192",
      "x": "0.571884738",
      "y": "0.146868175"
    },
    {
      "turn": "-0.267949192",
      "x": "0.190310025",
      "y": "0.073434088"
    },
    {
      "turn": "-0.267949192",
      "x": "0.444693167",
      "y": "0.073434088"
    },
    {
      "turn": "-0.267949192",
      "x": "0.699076309",
      "y": "0.073434088"
    }
  ],
  "radius": "0.146868174"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 31,
  "sides": 5
}

Starter answer

{
  "placements": [
    {
      "turn": "0.267949192",
      "x": "0.140296767",
      "y": "0.926565912"
    },
    {
      "turn": "0.267949192",
      "x": "0.394679909",
      "y": "0.926565912"
    },
    {
      "turn": "0.267949192",
      "x": "0.649063051",
      "y": "0.926565912"
    },
    {
      "turn": "-0.267949192",
      "x": "0.267488338",
      "y": "0.853131825"
    },
    {
      "turn": "-0.577350269",
      "x": "0.926565912",
      "y": "0.872808429"
    },
    {
      "turn": "-0.267949192",
      "x": "0.521871480",
      "y": "0.853131825"
    },
    {
      "turn": "0.000000000",
      "x": "0.853131825",
      "y": "0.745616858"
    },
    {
      "turn": "0.000000000",
      "x": "0.073434088",
      "y": "0.733506542"
    },
    {
      "turn": "-0.577350269",
      "x": "0.706263649",
      "y": "0.727928137"
    },
    {
      "turn": "0.267949192",
      "x": "0.335695605",
      "y": "0.706263649"
    },
    {
      "turn": "0.577350269",
      "x": "0.926565912",
      "y": "0.618425287"
    },
    {
      "turn": "-0.577350269",
      "x": "0.158020878",
      "y": "0.612753987"
    },
    {
      "turn": "0.000000000",
      "x": "0.632829561",
      "y": "0.600736566"
    },
    {
      "turn": "-0.552464823",
      "x": "0.482459254",
      "y": "0.564935541"
    },
    {
      "turn": "-0.000000000",
      "x": "0.304889053",
      "y": "0.492387264"
    },
    {
      "turn": "0.000000000",
      "x": "0.853131825",
      "y": "0.491233716"
    },
    {
      "turn": "0.000000000",
      "x": "0.084586790",
      "y": "0.485562416"
    },
    {
      "turn": "0.577350269",
      "x": "0.706263649",
      "y": "0.473544995"
    },
    {
      "turn": "-0.577350269",
      "x": "0.926565912",
      "y": "0.364042145"
    },
    {
      "turn": "0.577350269",
      "x": "0.158020878",
      "y": "0.358370845"
    },
    {
      "turn": "0.267949192",
      "x": "0.489258467",
      "y": "0.367170439"
    },
    {
      "turn": "-0.267949192",
      "x": "0.362066896",
      "y": "0.293736351"
    },
    {
      "turn": "-0.267949192",
      "x": "0.616450038",
      "y": "0.293736351"
    },
    {
      "turn": "-0.000000000",
      "x": "0.073434088",
      "y": "0.237618290"
    },
    {
      "turn": "0.054686686",
      "x": "0.826267880",
      "y": "0.236850574"
    },
    {
      "turn": "-0.506666415",
      "x": "0.913133940",
      "y": "0.118425287"
    },
    {
      "turn": "0.267949192",
      "x": "0.317501596",
      "y": "0.146868175"
    },
    {
      "turn": "0.267949192",
      "x": "0.571884738",
      "y": "0.146868175"
    },
    {
      "turn": "-0.267949192",
      "x": "0.190310025",
      "y": "0.073434088"
    },
    {
      "turn": "-0.267949192",
      "x": "0.444693167",
      "y": "0.073434088"
    },
    {
      "turn": "-0.267949192",
      "x": "0.699076309",
      "y": "0.073434088"
    }
  ],
  "radius": "0.146868174"
}

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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