Separations above TFNP from Sherali-Adams Lower Bounds by Deniz Imrek

Separations above TFNP from Sherali-Adams Lower Bounds by Deniz Imrek

🎙 Deniz Imrek 👥 74K 📅 September 28, 2026 ⏱ 35 min 👁 0 📄 original study 🧭 2026-09-28
Available in: English (current) Français

Keywords

TFNPSherali-Adams lower boundsProof complexitySigma-2 proof systemsTotal functional hierarchy

Summary

The talk presents an approach to prove separations in the complexity class TFNP and its higher-level analogue TF-sigma-2 using proof complexity. The speaker introduces the sigma-2 proof system, which extends classical proof systems by allowing preprocessing step of sigma-2 weakenings, enabling the use of DNF rather than only clauses. The main results are that LOP (Linear Ordering Principle) does not reduce to Strong Avoid, and LOP does not reduce to List Number. These separations are obtained via a Sherali-Adams lower bound in the sigma-2 setting. The proof technique reduces to a combinatorial covering problem: covering all total orders that do not start with a given element using fewer than k! tiles, and the talk establishes a lower bound for such coverings when k is sufficiently small. The presentation also includes a decomposition lemma showing that reductions in TF-sigma-2 can be factored into a sigma-2 weakening followed by a counter-example reduction, which preserves properties like low Sherali-Adams degree. Overall, the talk provides a novel framework for lifting proof complexity lower bounds to separations above TFNP.

174 words

Critical Evaluation

Value of the Information & Strength of the Argument

The value of the talk lies in its demonstration that proof complexity methods, traditionally used for TFNP separations, can be extended to the more expressive class TF-sigma-2. The argumentation is solid: the speaker carefully defines sigma-2 proof systems, shows how they characterize problems in TF-sigma-2, and then derives separations by proving lower bounds on the degree of Sherali-Adams proofs. The proof sketch is coherent, progressing from an abstract expectation-based argument to a concrete combinatorial covering problem. The results are non-trivial and answer open questions about the dominance of Strong Avoid in TF-sigma-2. The presentation is well-structured, though dense, making it suitable for an expert audience.

Scientific Rigor, Source Quality, Title Accuracy

The talk is scientifically rigorous, grounded in prior work by the speaker and collaborators, as well as classical results in proof complexity and total function problems. The sources are not explicitly cited inline, but the talk references key papers and constructs (e.g., the works of Kleinberg et al., Feige et al., and the speaker’s own recent papers). The provided description includes a link to the ICTS program page, which serves as a reference for the workshop context. The title accurately reflects the content. The talk does not go beyond well-established theoretical frameworks, and the technical details appear correct. The main limitation is that, without seeing the slides, some visual details are lost, but the transcript conveys the core arguments effectively.

240 words

Title / Content Match

The title accurately reflects the talk's central contribution: proving separations above TFNP using Sherali-Adams lower bounds.

Quality & Reliability

9/10

The talk presents rigorous results in computational complexity, with clear methodology and a detailed proof sketch, built on established frameworks.

Key Moments

Cited Sources

Contribution & Novelties

This talk presents novel results in computational complexity, specifically the first TF-sigma-2 problems that do not reduce to Strong Avoid. The formalization of sigma-2 proof systems and the use of Sherali-Adams lower bounds to derive separations is a significant contribution, extending the proof complexity approach from TFNP to higher levels of the total functional polynomial hierarchy. The talk also introduces a decomposition lemma that clarifies the structure of reductions in this setting.

Pour aller plus loin :

  • TFNP — The class of total function problems with efficiently verifiable solutions; the base class for this talk.
  • Proof complexity — The study of the lengths of proofs in various formal systems; central to the method used.
  • Sherali–Adams relaxation — A hierarchy for linear programming relaxations, used here for lower bounds on proof size.

131 words

Radar Profile

The profile shows an extremely high technical level (10/10) and high information quality (9/10), with a slightly lower quantity of information (8/10) due to the concentrated focus on a single result. The global reliability is high (9/10), indicating a trustworthy and well-supported presentation.

Reliability 9/10