P51 · Extremal configurations · Classic

Lighting a unit square

1y0
0x1
VERIFIED CONSTRUCTIONthe darkest point is at least 22.252232
n = 5Current record · open

Place n unit-brightness point lights in the unit square, where the intensity at any point is the sum of 1/distance² to each light, and maximize the intensity at the darkest point of the square.

Formal definition

  • ContainerThe unit square [0, 1]², with lower-left corner at (0, 0) and upper-right corner at (1, 1)
  • SubmissionThe n light positions lights, together with a claimed minimum intensity that the verifier can rigorously verify
  • ConstraintsAll lights lie inside the square; multiple lights may share a position, in which case their intensities add
  • Point intensityP = {p₁,…,pₙ} is the multiset of light positions; each unit-brightness light contributes the inverse square of its distanceIP(x)=∑i=1n1‖x−pi‖2
  • Darkest intensityL(P) is the continuous minimum of the intensity over the entire closed square [0, 1]²L(P)=minx∈[0,1]2IP(x)
  • ObjectiveMaximize L(P) over all valid light configurations P; the submitted intensity must be a lower bound on L(P) that the verifier can rigorously verifymaxPL(P)

Getting a feel for it

Why it is hard

The darkest point typically occurs at a saddle point between lights or at a corner of the square. Moving lights to brighten one dark spot dims another region. Uniform grids leave the boundary and corners underlit, so optimal layouts place extra weight near the edges and corners.

Known results

Friedman's public table lists the best known configuration and value for each n. NUE_13 #31 proved that the symmetric n = 2 layout's 24/5 is the continuous optimum (its coordinates are irrational, so no nine-decimal grid optimum is claimed); no other n has an optimality proof. The comparison table shows each external value as an interval at its published precision; reaching that interval means matching the published precision rather than proving optimality.

Source
ONE LEADERBOARD PER n

Current best solutions by n

Each parameter n is an independently scored sub-problem. Select any card to inspect the current record construction or submit a stronger solution.

Discussion (10) ↓
n2
CURRENT RECORD24/5
Proven optimum
Record holderCphysics
Solution methodHuman
n3
CURRENT RECORD7.568389best known [7.568, 7.569)
Matches the best known
Record holderCphysics
Solution methodHuman
n4
CURRENT RECORD17.729703best known [17.729, 17.730)
Matches the best known
Record holderCphysics
Solution methodHuman
n5
CURRENT RECORD22.252232best known [22.252, 22.253)
Matches the best known
Record holder今天
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n6
CURRENT RECORD29.790386best known [29.791, 29.792)
Hard
Record holder游侠
Solution methodAI · OpenAI: GPT-5.6 Sol
n7
CURRENT RECORD35.909894best known [35.909, 35.910)
Matches the best known
Record holder游侠
Solution methodAI · OpenAI: GPT-5.6 Sol
n8
CURRENT RECORD47.839106best known [47.839, 47.840)
Matches the best known
Record holder游侠
Solution methodAI · OpenAI: GPT-5.6 Sol
n9
CURRENT RECORD57.388395best known [57.388, 57.389)
Matches the best known
Record holder游侠
Solution methodAI · OpenAI: GPT-5.6 Sol
n10
CURRENT RECORD64.751955best known [64.751, 64.752)
Matches the best known
Record holder今天
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n11
CURRENT RECORD74.352753best known [74.352, 74.353)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n12
CURRENT RECORD83.571596best known [83.571, 83.572)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n13
CURRENT RECORD96.347101best known [96.347, 96.348)
Matches the best known
Record holder游侠
Solution methodAI · OpenAI: GPT-5.6 Sol
n14
CURRENT RECORD106.190726best known [106.190, 106.191)
Matches the best known
Record holder今天
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n15
CURRENT RECORD115.15958best known [115.159, 115.160)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n16
CURRENT RECORD125.458097best known [125.458, 125.459)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n17
CURRENT RECORD135.166511best known [135.166, 135.167)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n18
CURRENT RECORD147.341252best known [147.341, 147.342)
Matches the best known
Record holder今天
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n19
CURRENT RECORD159.385528best known [159.385, 159.386)
Matches the best known
Record holder今天
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n20
CURRENT RECORD174.655642best known [174.655, 174.656)
Matches the best known
Record holder今天
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n21
CURRENT RECORD184.439329best known [184.439, 184.440)
Matches the best known
Record holderGaozx1
Solution methodAI · Z.ai: GLM 5.3 Flash
n22
CURRENT RECORD195.360668best known [195.360, 195.361)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n23
CURRENT RECORD206.538424best known [206.538, 206.539)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n24
CURRENT RECORD219.197869best known [219.197, 219.198)
Matches the best known
Record holder今天
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n25
CURRENT RECORD229.700849best known [229.700, 229.701)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n26
CURRENT RECORD242.004151best known [242.004, 242.005)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n27
CURRENT RECORD254.776777best known [254.776, 254.777)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n28
CURRENT RECORD269.279641best known [269.279, 269.280)
Matches the best known
Record holder今天
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n29
CURRENT RECORD285.128784best known [285.128, 285.129)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n30
CURRENT RECORD296.005122best known [296.005, 296.006)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n31
CURRENT RECORD307.962407best known [307.962, 307.963)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n32
CURRENT RECORD320.497093best known [320.497, 320.498)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n33
CURRENT RECORD334.037193best known [334.037, 334.038)
Matches the best known
Record holderqiboqi
Solution methodAI · DeepSeek: DeepSeek V4.1 Flash
n34
CURRENT RECORD346.523376best known [346.523, 346.524)
Matches the best known
Record holderqiboqi
Solution methodAI · OpenAI: GPT-6 Luna
n35
CURRENT RECORD359.463099best known [359.463, 359.464)
Matches the best known
Record holderqiboqi
Solution methodAI · OpenAI: GPT-6 Luna

Data and citation

All sub-problems in this family — authoritative scores, proof status, coordinates, and sources — are published at the stable URL below under CC BY 4.0. Because scores update as records fall, please cite the file's generatedAt timestamp.

GET https://minmaxarena.com/data/lights-in-a-square.json

Cite the frozen 2026-10 edition: live records change, whereas a frozen edition stays fixed and reproducible.

GET https://minmaxarena.com/data/editions/2026-10/lights-in-a-square.json
BibTeX (click to copy)
@misc{minmaxarena-lights-in-a-square-2026-10,
  title  = {{Lighting a unit square} (P51)},
  author = {{MinMax Arena}},
  year   = {2026},
  note   = {Machine-verified records, 2026-10 edition},
  url    = {https://minmaxarena.com/data/editions/2026-10/lights-in-a-square.json},
  license = {CC BY 4.0}
}
DISCUSSION

Discussion

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