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Komlós conjecture

Maintainer — open

The Komlós conjecture There exists a universal constant K>0K > 0 such that for all n,mNn, m \in \mathbb{N} and all vectors v1,,vnRmv_1, \dots, v_n \in \mathbb{R}^m with vi21\|v_i\|_2 \le 1 (encoded here as jvij21\sum_j v_{ij}^2 \le 1), there exist signs εi{1,+1}\varepsilon_i \in \{-1, +1\} such that iεiviK\left\|\sum_i \varepsilon_i v_i\right\|_\infty \le K, i.e. iεivijK\left|\sum_i \varepsilon_i v_{ij}\right| \le K for ev

Motivation

The Komlós conjecture There exists a universal constant K>0K > 0 such that for all n,mNn, m \in \mathbb{N} and all vectors v1,,vnRmv_1, \dots, v_n \in \mathbb{R}^m with vi21\|v_i\|_2 \le 1 (encoded here as jvij21\sum_j v_{ij}^2 \le 1), there exist signs εi{1,+1}\varepsilon_i \in \{-1, +1\} such that iεiviK\left\|\sum_i \varepsilon_i v_i\right\|_\infty \le K, i.e. iεivijK\left|\sum_i \varepsilon_i v_{ij}\right| \le K for every coordinate jj.

Adapted from formal-conjectures, Wikipedia/KomlosConjecture.lean. Catalogued at https://en.wikipedia.org/wiki/Discrepancy_theory#Major_open_problems.

Lean API
import Mathlib

namespace Conjectura.WP0021

/-- **The Komlós conjecture** There exists a universal constant $K > 0$ such that for all $n, m \in \mathbb{N}$ and all vectors $v_1, \dots, v_n \in \mathbb{R}^m$ with $\|v_i\|_2 \le 1$ (encoded here as $\sum_j v_{ij}^2 \le 1$), there exist signs $\varepsilon_i \in \{-1, +1\}$ such that $\left\|\sum_i \varepsilon_i v_i\right\|_\infty \le K$, i.e. $\left|\sum_i \varepsilon_i v_{ij}\right| \le K$ for every coordinate $j$. -/
def goal : Prop :=
  ∃ K : ℝ, 0 < K ∧ ∀ (n m : ℕ) (v : Fin n → Fin m → ℝ),
      (∀ i, ∑ j, (v i j) ^ 2 ≤ 1) →
      ∃ ε : Fin n → ℝ, (∀ i, ε i = 1 ∨ ε i = -1) ∧
        ∀ j, |∑ i, ε i * v i j| ≤ K

end Conjectura.WP0021
Definition

This statement is written entirely in arithmetic and standard number systems — there is no specialised vocabulary to define.

Related work2
  • Komlós conjecture

    The catalogue entry, with references and status.

  • formal-conjecturesThe Formal Conjectures Authors (Google DeepMind) · 2025

    Source of the Lean formalization adapted here.

For your AI
Download as .md
I am proving a theorem in Lean 4 and submitting it to Conjectura.

## Problem WP0021 — Komlós conjecture

**The Komlós conjecture** There exists a universal constant $K > 0$ such that for all $n, m \in \mathbb{N}$ and all vectors $v_1, \dots, v_n \in \mathbb{R}^m$ with $\|v_i\|_2 \le 1$ (encoded here as $\sum_j v_{ij}^2 \le 1$), there exist signs $\varepsilon_i \in \{-1, +1\}$ such that $\left\|\sum_i \varepsilon_i v_i\right\|_\infty \le K$, i.e. $\left|\sum_i \varepsilon_i v_{ij}\right| \le K$ for ev

## Environment (fixed — do not assume anything newer)

- Lean toolchain: `leanprover/lean4:v4.33.0-rc1`
- Mathlib: `v4.33.0-rc1`

If a lemma you want does not exist in that Mathlib, prove it inline instead of
importing something newer.

## The exact statement I must prove

```lean
theorem solution : Conjectura.WP0021.goal := by
  sorry
```

## The file I submit

```lean
import Conjectura.Problems.WP0021.Statement

namespace Submission

theorem solution : Conjectura.WP0021.goal := by
  sorry

end Submission

```

## The Lean definitions of every term in this problem

These are the actual definitions your proof will be checked against. Do not
substitute your own version of any of them.

(none)

## Rules — submissions violating these are rejected automatically

1. **Do not change the name or type of `solution`.** It must satisfy the
   statement above exactly.
2. **Do not redefine or shadow anything from the problem's Statement module.**
   Declaring your own `goal`, or redefining a name it depends on, produces a
   proof of a *different* statement and is rejected. This is the single most
   common rejection.
3. **No `sorry`** anywhere, including in helper lemmas. It surfaces as the
   axiom `sorryAx` and is detected transitively through imports.
4. **No `native_decide`** — it surfaces as `Lean.ofReduceBool` and is not
   accepted, because it trusts compiled code rather than the kernel.
5. Only these axioms are permitted: `propext`, `Classical.choice`,
   `Quot.sound`.
6. Follow Mathlib style: hypotheses left of the colon, explicit types,
   `snake_case` theorem names, `UpperCamelCase` types.

## What I want from you

Here is my argument in informal mathematics:

> [PASTE YOUR PROOF SKETCH HERE]

Turn it into Lean 4 that compiles under the environment above and satisfies the
statement exactly. Where you are unsure a lemma exists in this Mathlib version,
say so explicitly rather than guessing a name.

Submissions are not open yet

Conjectura is in beta. You can read every statement, every definition and the Lean behind them, and download the exact files the checker uses — but proofs are not being accepted yet.

The reason is a deliberate order of operations. Accepting a proof means running a stranger’s code and standing behind a verdict, and no statement here yet carries a researcher’s name. A machine-checked answer to a question nobody has vouched for is worth very little, so the vouching comes first.

The English write-ups are also switched off during the beta. Nothing on this page is generated by a model.

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