Furthest Pair Requires Quadratic Time in Superconstant Dimension under SETH

Barna Saha, Yinzhan Xu, Christopher Ye

Under OVH or SETH, Saha, Xu and Ye prove n^(2−o(1)) lower bounds for exact Furthest Pair, Bichromatic Closest Pair, Maximum Inner Product and Hopcroft’s problem in every efficiently constructible superconstant dimension.

Sources for this record

What was already known

Earlier SETH hardness reached dimensions of order 2^Θ(log* n), leaving the smaller superconstant range open.

AI involvement AI-led

ChatGPT 5.5 Pro generated the initial proof after the authors suggested a proof direction. Saha, Xu and Ye validated, edited and explained the complete argument.

ChatGPT generated the initial full proof and key OV-to-integer-OV reduction; humans supplied a proof-technique prompt and validated the result.

Importance Major

The conditional theorem closes the dimension gap for several fine-grained geometric problems.

Limitations

The lower bounds depend on OVH or SETH. Lean formalizes the key local embedding lemma under three algebraic-number-theory inputs, while the full reductions are author-checked.

Technical verification Formal (Lean 4 (Lemma 3.1 only) + human)

The authors report validating the full proof by hand. The Lean check covers only the key embedding lemma and is conditional on three standard number-theory inputs.

Formal checking

Author validation and substantial mathematical editing of the proof

Checker
Saha, Xu and Ye
Scope
Final conditional hardness theorem and reductions
Basis
Reported by the linked checker

Lean formalization with three algebraic-number-theory assumptions

Checker
Aristotle/Lean 4, as reported by authors
Scope
Lemma 3.1, improved local OV-to-integer-OV embedding
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 give a detailed technical overview of the number-theoretic encoding and final reductions.

Correction and publication history

2026-10-18 · publication

The conditional theorem closes the dimension gap for several fine-grained geometric problems.

Read this published revision