P82 · Packing and covering · Classic · Hard

Equal circles in regular polygons · m = 5 · n = 31

Pack n equal circles into the true regular m-gon with centre (1,1), circumradius 1 and first vertex (2,1), maximising their radius.

Instancem = 5 · n = 31
ObjectiveMaximize circle radius

Formal definition

  • ContainerThe editor and certificate normalize to the true regular m-gon with centre (1,1), circumradius 1 and first vertex (2,1). This is a coordinate convention only; scores use the literature's unit-piece scale. Boundary contact is allowed.
  • SubmissionSubmit {radius, placements:[{x,y,turn},…]}, with decimal strings of at most nine places. x,y are centres; circles require turn=0, polygons use turn=tan(θ/2). Coordinates and turn lie in ±4; 0 < radius ≤ 4.
  • ConstraintsExactly n congruent shapes lie wholly in the container with pairwise disjoint interiors. Polygon rotations are independent, not limited to quarter turns.
  • PrecisionInput decimals are exact rationals; regular-polygon vertices are algebraic, not rounded templates. Feasibility has no floating-point tolerance. A finite-decimal certificate is not a continuous optimality proof.
  • ObjectiveCircle radius r, larger is better; the container circumradius is 1.
Open the full editor
VERIFIED CONSTRUCTIONVERIFIED CONSTRUCTION

Getting a feel for it

Source and certificate

External targets are converted with their printed precision; decimal coordinate certificates are separate. Reconstruction loss never lowers the literature target, and a source construction is not automatically an optimality proof.

Source
The record-holding arrangement for Equal circles in regular polygons m = 5 · n = 31, 0.138616361
Current leader

0.138616361

circle radius

Answer sourceEckard Specht
Solution methodPublished reference construction
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Record holder's solver noteNo solver note yet (expand)

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ANSWER FORMAT

How to write your answer

the true regular m-gon with centre (1,1), circumradius 1 and first vertex (2,1)

Submit {radius, placements:[{x,y,turn},…]}, with decimal strings of at most nine places. x,y are centres; circles require turn=0, polygons use turn=tan(θ/2). Coordinates and turn lie in ±4; 0 < radius ≤ 4.

The current leader's answer

{
  "placements": [
    {
      "turn": "0",
      "x": "0.329599368",
      "y": "1.487074570"
    },
    {
      "turn": "0",
      "x": "0.329599368",
      "y": "1.116064768"
    },
    {
      "turn": "0",
      "x": "0.329599368",
      "y": "0.790158154"
    },
    {
      "turn": "0",
      "x": "0.329599368",
      "y": "0.512925430"
    },
    {
      "turn": "0",
      "x": "0.535623432",
      "y": "1.301569669"
    },
    {
      "turn": "0",
      "x": "0.553885353",
      "y": "0.953111461"
    },
    {
      "turn": "0",
      "x": "0.569689950",
      "y": "0.651541792"
    },
    {
      "turn": "0",
      "x": "0.593263357",
      "y": "1.572744193"
    },
    {
      "turn": "0",
      "x": "0.682450658",
      "y": "0.398277096"
    },
    {
      "turn": "0",
      "x": "0.759909418",
      "y": "1.138616362"
    },
    {
      "turn": "0",
      "x": "0.793975935",
      "y": "0.814495099"
    },
    {
      "turn": "0",
      "x": "0.817549342",
      "y": "1.409790886"
    },
    {
      "turn": "0",
      "x": "0.903218966",
      "y": "1.673454876"
    },
    {
      "turn": "0",
      "x": "0.906736643",
      "y": "0.561230403"
    },
    {
      "turn": "0",
      "x": "0.992406266",
      "y": "0.297566414"
    },
    {
      "turn": "0",
      "x": "1.000000000",
      "y": "1.000000000"
    },
    {
      "turn": "0",
      "x": "1.057639924",
      "y": "1.271174524"
    },
    {
      "turn": "0",
      "x": "1.112760708",
      "y": "0.746735304"
    },
    {
      "turn": "0",
      "x": "1.143309548",
      "y": "1.534838513"
    },
    {
      "turn": "0",
      "x": "1.198430331",
      "y": "0.483071315"
    },
    {
      "turn": "0",
      "x": "1.256070255",
      "y": "1.788103209"
    },
    {
      "turn": "0",
      "x": "1.256070255",
      "y": "0.211896791"
    },
    {
      "turn": "0",
      "x": "1.275714015",
      "y": "1.028978711"
    },
    {
      "turn": "0",
      "x": "1.333353939",
      "y": "1.300153235"
    },
    {
      "turn": "0",
      "x": "1.388474722",
      "y": "0.775714015"
    },
    {
      "turn": "0",
      "x": "1.419023562",
      "y": "1.563817224"
    },
    {
      "turn": "0",
      "x": "1.474144345",
      "y": "0.512050025"
    },
    {
      "turn": "0",
      "x": "1.552946739",
      "y": "1.028978711"
    },
    {
      "turn": "0",
      "x": "1.610586663",
      "y": "1.300153235"
    },
    {
      "turn": "0",
      "x": "1.665707447",
      "y": "0.775714015"
    },
    {
      "turn": "0",
      "x": "1.828660754",
      "y": "1.000000000"
    }
  ],
  "radius": "0.138616361"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer

Instance parameters

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

The current leader's answer

{
  "placements": [
    {
      "turn": "0",
      "x": "0.329599368",
      "y": "1.487074570"
    },
    {
      "turn": "0",
      "x": "0.329599368",
      "y": "1.116064768"
    },
    {
      "turn": "0",
      "x": "0.329599368",
      "y": "0.790158154"
    },
    {
      "turn": "0",
      "x": "0.329599368",
      "y": "0.512925430"
    },
    {
      "turn": "0",
      "x": "0.535623432",
      "y": "1.301569669"
    },
    {
      "turn": "0",
      "x": "0.553885353",
      "y": "0.953111461"
    },
    {
      "turn": "0",
      "x": "0.569689950",
      "y": "0.651541792"
    },
    {
      "turn": "0",
      "x": "0.593263357",
      "y": "1.572744193"
    },
    {
      "turn": "0",
      "x": "0.682450658",
      "y": "0.398277096"
    },
    {
      "turn": "0",
      "x": "0.759909418",
      "y": "1.138616362"
    },
    {
      "turn": "0",
      "x": "0.793975935",
      "y": "0.814495099"
    },
    {
      "turn": "0",
      "x": "0.817549342",
      "y": "1.409790886"
    },
    {
      "turn": "0",
      "x": "0.903218966",
      "y": "1.673454876"
    },
    {
      "turn": "0",
      "x": "0.906736643",
      "y": "0.561230403"
    },
    {
      "turn": "0",
      "x": "0.992406266",
      "y": "0.297566414"
    },
    {
      "turn": "0",
      "x": "1.000000000",
      "y": "1.000000000"
    },
    {
      "turn": "0",
      "x": "1.057639924",
      "y": "1.271174524"
    },
    {
      "turn": "0",
      "x": "1.112760708",
      "y": "0.746735304"
    },
    {
      "turn": "0",
      "x": "1.143309548",
      "y": "1.534838513"
    },
    {
      "turn": "0",
      "x": "1.198430331",
      "y": "0.483071315"
    },
    {
      "turn": "0",
      "x": "1.256070255",
      "y": "1.788103209"
    },
    {
      "turn": "0",
      "x": "1.256070255",
      "y": "0.211896791"
    },
    {
      "turn": "0",
      "x": "1.275714015",
      "y": "1.028978711"
    },
    {
      "turn": "0",
      "x": "1.333353939",
      "y": "1.300153235"
    },
    {
      "turn": "0",
      "x": "1.388474722",
      "y": "0.775714015"
    },
    {
      "turn": "0",
      "x": "1.419023562",
      "y": "1.563817224"
    },
    {
      "turn": "0",
      "x": "1.474144345",
      "y": "0.512050025"
    },
    {
      "turn": "0",
      "x": "1.552946739",
      "y": "1.028978711"
    },
    {
      "turn": "0",
      "x": "1.610586663",
      "y": "1.300153235"
    },
    {
      "turn": "0",
      "x": "1.665707447",
      "y": "0.775714015"
    },
    {
      "turn": "0",
      "x": "1.828660754",
      "y": "1.000000000"
    }
  ],
  "radius": "0.138616361"
}

Submit {radius, placements:[{x,y,turn},…]}, with decimal strings of at most nine places. x,y are centres; circles require turn=0, polygons use turn=tan(θ/2). Coordinates and turn lie in ±4; 0 < radius ≤ 4. · Verifier v1.0.0

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