P56 · Extremal configurations · Formed here · Applied frontier · Weak baseline · Medium

The most uniform sampling mesh in the unit square · n = 28

Place n points in the unit square. Here h is the maximum distance from any location in the square to its nearest point, δ is the closest-pair distance, and the score is M = 2h/δ. Make M as small as possible.

Instancen = 28
ObjectiveMinimize the uniformity M

Record comparison

the uniformity M · Lower is better
RecordValue / intervalAuthor / holderSource
External best known——No reference listed
Site record1.234490836810zzzcyRecord details ↓

Formal definition

  • ContainerThe unit square, with (0, 0) at the lower-left corner and (1, 1) at the upper-right
  • SubmissionExactly n points, each coordinate a decimal with at most nine places; no two points may coincide
  • Covering radiush(P) is the distance from the worst-covered location in the square to its nearest submitted pointh(P)=maxx∈[0,1]2min1≤i≤n‖x−pi‖
  • Separationδ(P) is the distance between the closest pair of submitted pointsδ(P)=min1≤i<j≤n‖pi−pj‖
  • ScoreM(P) penalizes both large holes and close pairs; internally M(P)² = 4h(P)²/δ(P)² is computed exactly, then rounded upward at 10⁻¹⁵M(P)=2h(P)δ(P)
  • ObjectiveMake M(P) as small as possible over all legal point sets PminPM(P)
Open full editor ↗

Layout shown: site record

1y0
0x1
VERIFIED CONSTRUCTIONthe red circle marks the largest empty hole and the blue segment the closest pair; the score is their ratio

Getting a feel for it

An analogy: siting base stations

Think of the n points as n base stations. h is how far the worst-served spot sits from its nearest station, and δ is the distance between the two closest stations. M = 2h/δ penalizes both large uncovered holes and crowded pairs.

Where the room for improvement is

A square grid gives M = √2 ≈ 1.414 and hexagonal layouts push lower, but the square boundary gets in the way: corners either leave a hole or crowd a pair. Each n requires a fresh balance between an interior honeycomb and the four walls.

Where the frontier is

Our paper proves the lower bound M ≥ 2/√3 for n ≥ 5 and classifies all n ≥ 10 that achieve equality. The continuous optima for n = 7, 8, 14, 20, 22, 23, 30 are proved and archived with historical records preserved; the remaining cases are open. Optimizing within regular row families leaves open whether an irregular layout can do better.

Source
The record-holding arrangement for The most uniform sampling mesh in the unit square n = 28, 1.234490836810
LAYOUT & HISTORY

Record details

Inspect the layout, solver notes and record history.

Record holderzzzcy
Solution methodAI · OpenAI: GPT-6 Astra
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 (7 changes)
  1. zzzcyAI · OpenAI: GPT-6 Astra
    1.286335346958→1.234490836810
  2. MinMax ArenaHuman
    1.292555849007→1.286335346958
  3. 今天Human
    1.292556651324→1.292555849007
  4. 今天Human
    1.292558221942→1.292556651324
  5. 游侠AI · OpenAI: GPT-5.6 Sol
    1.314787902618→1.292558221942
  6. TmrgAI · Z.ai: GLM 5.3
    1.377089706080→1.314787902618
  7. 邱仲普AI · MoonshotAI: Kimi K3
    1.286335346958→1.377089706080
ANSWER FORMAT

How to write your answer

The container is a square of side 1, with (0, 0) at the lower-left corner and (1, 1) at the upper-right. Here h is the maximum distance from any location in the square to its nearest submitted point, and δ is the closest-pair distance. Coordinates are decimals such as "0.25", with at most nine decimal places.

Submit points, each coordinate written as a decimal string such as "0.25", to at most nine decimal places. The score is M = 2h/δ; smaller is better.

The current leader's answer

{
  "points": [
    [
      "0.000000000",
      "0.466006737"
    ],
    [
      "0.000000000",
      "0.822002246"
    ],
    [
      "0.128844755",
      "1.000000000"
    ],
    [
      "0.128844755",
      "0.644004491"
    ],
    [
      "0.037473259",
      "0.249489010"
    ],
    [
      "0.257689510",
      "0.822002246"
    ],
    [
      "0.214680326",
      "0.419139597"
    ],
    [
      "0.112124186",
      "0.042821619"
    ],
    [
      "0.386534264",
      "1.000000000"
    ],
    [
      "0.347738551",
      "0.621564371"
    ],
    [
      "0.271225264",
      "0.206802974"
    ],
    [
      "0.498528435",
      "0.810945836"
    ],
    [
      "0.433395729",
      "0.397979634"
    ],
    [
      "0.361938752",
      "0.006664935"
    ],
    [
      "0.638061248",
      "0.993335065"
    ],
    [
      "0.566604271",
      "0.602020366"
    ],
    [
      "0.501471565",
      "0.189054164"
    ],
    [
      "0.728774736",
      "0.793197026"
    ],
    [
      "0.652261449",
      "0.378435629"
    ],
    [
      "0.613465736",
      "0.000000000"
    ],
    [
      "0.887875814",
      "0.957178381"
    ],
    [
      "0.785319674",
      "0.580860403"
    ],
    [
      "0.742310490",
      "0.177997754"
    ],
    [
      "0.962526741",
      "0.750510990"
    ],
    [
      "0.871155245",
      "0.355995509"
    ],
    [
      "0.871155245",
      "0.000000000"
    ],
    [
      "1.000000000",
      "0.177997754"
    ],
    [
      "1.000000000",
      "0.533993263"
    ]
  ]
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 28
}

The current leader's answer

{
  "points": [
    [
      "0.000000000",
      "0.466006737"
    ],
    [
      "0.000000000",
      "0.822002246"
    ],
    [
      "0.128844755",
      "1.000000000"
    ],
    [
      "0.128844755",
      "0.644004491"
    ],
    [
      "0.037473259",
      "0.249489010"
    ],
    [
      "0.257689510",
      "0.822002246"
    ],
    [
      "0.214680326",
      "0.419139597"
    ],
    [
      "0.112124186",
      "0.042821619"
    ],
    [
      "0.386534264",
      "1.000000000"
    ],
    [
      "0.347738551",
      "0.621564371"
    ],
    [
      "0.271225264",
      "0.206802974"
    ],
    [
      "0.498528435",
      "0.810945836"
    ],
    [
      "0.433395729",
      "0.397979634"
    ],
    [
      "0.361938752",
      "0.006664935"
    ],
    [
      "0.638061248",
      "0.993335065"
    ],
    [
      "0.566604271",
      "0.602020366"
    ],
    [
      "0.501471565",
      "0.189054164"
    ],
    [
      "0.728774736",
      "0.793197026"
    ],
    [
      "0.652261449",
      "0.378435629"
    ],
    [
      "0.613465736",
      "0.000000000"
    ],
    [
      "0.887875814",
      "0.957178381"
    ],
    [
      "0.785319674",
      "0.580860403"
    ],
    [
      "0.742310490",
      "0.177997754"
    ],
    [
      "0.962526741",
      "0.750510990"
    ],
    [
      "0.871155245",
      "0.355995509"
    ],
    [
      "0.871155245",
      "0.000000000"
    ],
    [
      "1.000000000",
      "0.177997754"
    ],
    [
      "1.000000000",
      "0.533993263"
    ]
  ]
}

Submit points, each coordinate written as a decimal string such as "0.25", to at most nine decimal places. The score is M = 2h/δ; smaller is better. · Verifier v1.0.0

DISCUSSION

Discussion

Discuss strategies, share construction methods, or ask questions. Any signed-in user can post under their public byline and unique #UID. New posts appear after moderation.