P85 · Packing and covering · Classic · Hard

Squares in an equilateral triangle · n = 39

Pack n unit squares into an equilateral triangle container with boundary contact allowed and disjoint interiors, minimising the side length of the container triangle.

Instancen = 39
ObjectiveMinimize container triangle side

Record comparison

container triangle side · Lower is better
RecordValue / intervalAuthor / holderSource
External best known[10.3094, 10.30941)Bhavithran AnanthanErich Friedman ↗
Site recordNo player record yet——

Formal definition

  • ContainerThe editor and certificate normalise the container to the equilateral triangle with vertices (0,0), (1,0), and (1/2,√3/2), 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 triangle side = 1/(2 sin(π/4) r), where smaller is better. Pages, leaderboards, and literature records share this unit with automatic conversion.
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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.

Source
The current arrangement for Squares in an equilateral triangle n = 39
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 equilateral triangle with vertices (0,0), (1,0), (1/2,√3/2)

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": "0.131652498",
      "x": "0.489750866",
      "y": "0.751274538"
    },
    {
      "turn": "0.131652498",
      "x": "0.441251443",
      "y": "0.667271074"
    },
    {
      "turn": "-0.131652498",
      "x": "0.566251443",
      "y": "0.654275692"
    },
    {
      "turn": "0.131652498",
      "x": "0.394877386",
      "y": "0.582040529"
    },
    {
      "turn": "-0.131652498",
      "x": "0.613974006",
      "y": "0.569823708"
    },
    {
      "turn": "-0.300059210",
      "x": "0.509285537",
      "y": "0.532986350"
    },
    {
      "turn": "0.131652498",
      "x": "0.344519242",
      "y": "0.499110198"
    },
    {
      "turn": "-0.131652498",
      "x": "0.659465431",
      "y": "0.484083576"
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    {
      "turn": "0.077928099",
      "x": "0.431990814",
      "y": "0.444528394"
    },
    {
      "turn": "-0.300667504",
      "x": "0.555662555",
      "y": "0.443022989"
    },
    {
      "turn": "0.131652498",
      "x": "0.298147343",
      "y": "0.413878408"
    },
    {
      "turn": "-0.131652498",
      "x": "0.711288098",
      "y": "0.401998787"
    },
    {
      "turn": "0.093828102",
      "x": "0.382012868",
      "y": "0.358510919"
    },
    {
      "turn": "-0.230352285",
      "x": "0.622770031",
      "y": "0.344498847"
    },
    {
      "turn": "-0.251180699",
      "x": "0.522305259",
      "y": "0.332883942"
    },
    {
      "turn": "0.131652498",
      "x": "0.247709274",
      "y": "0.330994222"
    },
    {
      "turn": "-0.131652498",
      "x": "0.759994586",
      "y": "0.318114872"
    },
    {
      "turn": "0.127116306",
      "x": "0.320660764",
      "y": "0.262335517"
    },
    {
      "turn": "-0.111052614",
      "x": "0.681756833",
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    },
    {
      "turn": "0.131652498",
      "x": "0.198754833",
      "y": "0.247253463"
    },
    {
      "turn": "-0.407488738",
      "x": "0.435996114",
      "y": "0.243091269"
    },
    {
      "turn": "-0.242739443",
      "x": "0.554851406",
      "y": "0.240587007"
    },
    {
      "turn": "-0.131652498",
      "x": "0.808659291",
      "y": "0.234206834"
    },
    {
      "turn": "-0.123651604",
      "x": "0.734558408",
      "y": "0.166949253"
    },
    {
      "turn": "0.131652498",
      "x": "0.150254908",
      "y": "0.163250289"
    },
    {
      "turn": "-0.249444697",
      "x": "0.615691221",
      "y": "0.157552155"
    },
    {
      "turn": "-0.131652498",
      "x": "0.857247979",
      "y": "0.150254908"
    },
    {
      "turn": "-0.397766418",
      "x": "0.274473662",
      "y": "0.146848342"
    },
    {
      "turn": "0.414513407",
      "x": "0.372801353",
      "y": "0.145529739"
    },
    {
      "turn": "-0.404302325",
      "x": "0.470593428",
      "y": "0.146324173"
    },
    {
      "turn": "-0.131652498",
      "x": "0.905747402",
      "y": "0.066251443"
    },
    {
      "turn": "-0.414213562",
      "x": "0.686494804",
      "y": "0.051796680"
    },
    {
      "turn": "0.414213562",
      "x": "0.395498268",
      "y": "0.048504698"
    },
    {
      "turn": "0.414213562",
      "x": "0.492497113",
      "y": "0.048798717"
    },
    {
      "turn": "0.414213562",
      "x": "0.104501732",
      "y": "0.048499423"
    },
    {
      "turn": "0.414213562",
      "x": "0.201500577",
      "y": "0.048499423"
    },
    {
      "turn": "0.414213562",
      "x": "0.298499423",
      "y": "0.048506077"
    },
    {
      "turn": "0.414213562",
      "x": "0.589495958",
      "y": "0.048499436"
    },
    {
      "turn": "0.414213562",
      "x": "0.783493649",
      "y": "0.048499423"
    }
  ],
  "radius": "0.068588540"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 39,
  "sides": 5
}

Starter answer

{
  "placements": [
    {
      "turn": "0.131652498",
      "x": "0.489750866",
      "y": "0.751274538"
    },
    {
      "turn": "0.131652498",
      "x": "0.441251443",
      "y": "0.667271074"
    },
    {
      "turn": "-0.131652498",
      "x": "0.566251443",
      "y": "0.654275692"
    },
    {
      "turn": "0.131652498",
      "x": "0.394877386",
      "y": "0.582040529"
    },
    {
      "turn": "-0.131652498",
      "x": "0.613974006",
      "y": "0.569823708"
    },
    {
      "turn": "-0.300059210",
      "x": "0.509285537",
      "y": "0.532986350"
    },
    {
      "turn": "0.131652498",
      "x": "0.344519242",
      "y": "0.499110198"
    },
    {
      "turn": "-0.131652498",
      "x": "0.659465431",
      "y": "0.484083576"
    },
    {
      "turn": "0.077928099",
      "x": "0.431990814",
      "y": "0.444528394"
    },
    {
      "turn": "-0.300667504",
      "x": "0.555662555",
      "y": "0.443022989"
    },
    {
      "turn": "0.131652498",
      "x": "0.298147343",
      "y": "0.413878408"
    },
    {
      "turn": "-0.131652498",
      "x": "0.711288098",
      "y": "0.401998787"
    },
    {
      "turn": "0.093828102",
      "x": "0.382012868",
      "y": "0.358510919"
    },
    {
      "turn": "-0.230352285",
      "x": "0.622770031",
      "y": "0.344498847"
    },
    {
      "turn": "-0.251180699",
      "x": "0.522305259",
      "y": "0.332883942"
    },
    {
      "turn": "0.131652498",
      "x": "0.247709274",
      "y": "0.330994222"
    },
    {
      "turn": "-0.131652498",
      "x": "0.759994586",
      "y": "0.318114872"
    },
    {
      "turn": "0.127116306",
      "x": "0.320660764",
      "y": "0.262335517"
    },
    {
      "turn": "-0.111052614",
      "x": "0.681756833",
      "y": "0.255310021"
    },
    {
      "turn": "0.131652498",
      "x": "0.198754833",
      "y": "0.247253463"
    },
    {
      "turn": "-0.407488738",
      "x": "0.435996114",
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    },
    {
      "turn": "-0.242739443",
      "x": "0.554851406",
      "y": "0.240587007"
    },
    {
      "turn": "-0.131652498",
      "x": "0.808659291",
      "y": "0.234206834"
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    {
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    {
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    {
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    {
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    },
    {
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    {
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      "x": "0.372801353",
      "y": "0.145529739"
    },
    {
      "turn": "-0.404302325",
      "x": "0.470593428",
      "y": "0.146324173"
    },
    {
      "turn": "-0.131652498",
      "x": "0.905747402",
      "y": "0.066251443"
    },
    {
      "turn": "-0.414213562",
      "x": "0.686494804",
      "y": "0.051796680"
    },
    {
      "turn": "0.414213562",
      "x": "0.395498268",
      "y": "0.048504698"
    },
    {
      "turn": "0.414213562",
      "x": "0.492497113",
      "y": "0.048798717"
    },
    {
      "turn": "0.414213562",
      "x": "0.104501732",
      "y": "0.048499423"
    },
    {
      "turn": "0.414213562",
      "x": "0.201500577",
      "y": "0.048499423"
    },
    {
      "turn": "0.414213562",
      "x": "0.298499423",
      "y": "0.048506077"
    },
    {
      "turn": "0.414213562",
      "x": "0.589495958",
      "y": "0.048499436"
    },
    {
      "turn": "0.414213562",
      "x": "0.783493649",
      "y": "0.048499423"
    }
  ],
  "radius": "0.068588540"
}

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

Discussion

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