Counterexamples to Wegner's Conjecture for Rectangles

Deepak Ajwani, Rishikesh Gajjala, Rajiv Raman, Saurabh Ray

Ajwani, Gajjala, Raman and Ray give 64 axis-parallel rectangles with packing number 16 and piercing number at least 32, disproving Wegner’s proposed bound 2ν−1. Their package construction yields piercing and clique-LP ratios approaching 5/2.

Sources for this record

What was already known

Wegner's 1965 conjecture bounded the piercing number by 2ν−1. Earlier rectangle examples reached 5/3, while a diagonal-line construction approached ratio 2 without violating the conjecture; earlier clique-LP lower bounds reached approximately 2.

AI involvement AI-centered

GPT-5.5 Pro helped search for rectangle counterexamples, including search code. Ajwani, Gajjala, Raman and Ray distilled the promising constructions and wrote and checked the final proofs.

The documented model-run search produced promising rectangle counterexamples that the authors distilled into the central construction; the final proof and generalization remain credited to the authors.

Importance Notable

Disproves Wegner’s rectangle-piercing bound and raises the known lower ratio toward 5/2.

Limitations

The separate LP upper bound and chromatic construction are additional results of the authors. The paper does not identify which final coordinates or parameters first appeared in model output.

Technical verification Formal (human)

All mathematical proofs were reviewed and rewritten by the four human authors, including the explicit counterexample and grid-package generalization. This is an author-reported complete human proof review, not a reproduced check. Auxiliary integer programs and Lean work have no stated theorem-matching scope here.

Formal checking

All mathematical proofs were reviewed and rewritten by the four human authors, including the explicit counterexample and grid-package generalization. This is an author-reported complete human proof review, not a reproduced check. Auxiliary integer programs and Lean work have no stated theorem-matching scope here.

Checker
Ajwani, Gajjala, Raman and Ray, the paper's human authors
Scope
The rectangle counterexample and generalized package construction disproving Wegner's bound
Basis
Reported by the linked checker
Evidence source

Checking a formal statement does not establish that it matches the original problem.

Human understanding Full

The authors explain the eight-rectangle package, grid composition and port-count argument, including why the family is triangle-free and has packing number 16.

Correction and publication history

2026-10-18 · publication

The AI search supplied promising counterexamples; the four authors distilled the construction and checked the proofs.

Read this published revision