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arxiv: 2604.04676 · v1 · submitted 2026-04-06 · 🧮 math.AP · math.FA

A Trudinger-Moser inequality under a refined constraint in fractional dimensions and extremal functions

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classification 🧮 math.AP math.FA
keywords Trudinger-Moser inequalityTintarev constraintfractional dimensionsSobolev spacesextremal functionsmaximizerscritical regime
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The pith

A Trudinger-Moser inequality with Tintarev constraint holds and attains its supremum in fractional dimensions.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper establishes a Trudinger-Moser type inequality that incorporates a refined Tintarev-type constraint, set in fractional-dimensional spaces, and shows that the supremum is attained by extremal functions when the exponent reaches its critical value. This refines earlier versions of the inequality both for fractional dimensions and for standard Sobolev spaces. A reader would care because the inequality governs the exponential integrability of functions whose fractional Sobolev norm is controlled, which is the borderline case between Sobolev embeddings and Orlicz spaces. The existence of maximizers turns the inequality into a sharp tool that can be used directly in variational problems.

Core claim

We establish a Trudinger-Moser type inequality with a Tintarev-type constraint in fractional-dimensional spaces and prove the existence of maximizers in the critical regime. Our results provide a refinement of those in Calc. Var. 52 (2015), 125-163 in the setting of fractional-dimensional spaces, as well as of those in Ann. Global Anal. Geom. 54 (2018), 237-256 for classical Sobolev spaces.

What carries the argument

The Tintarev-type constraint, a refined restriction imposed on functions in the fractional Sobolev space that restores the compactness required for the variational problem to attain its supremum.

Load-bearing premise

The fractional-dimensional Sobolev spaces possess the embeddings and compactness properties needed under the refined constraint so that the supremum is attained.

What would settle it

A sequence of functions obeying the Tintarev constraint whose associated Trudinger-Moser functional values exceed the claimed bound, or a maximizing sequence that fails to converge strongly to any limit function.

read the original abstract

We establish a Trudinger-Moser type inequality with a Tintarev-type constraint in fractional-dimensional spaces and prove the existence of maximizers in the critical regime. Our results provide a refinement of those in (Calc. Var. 52 (2015), 125-163) in the setting of fractional-dimensional spaces, as well as of those in (Ann. Global Anal. Geom. 54 (2018), 237-256) for classical Sobolev spaces.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 2 minor

Summary. The manuscript establishes a Trudinger-Moser type inequality incorporating a Tintarev-type constraint in fractional-dimensional spaces and proves the existence of maximizers in the critical regime. It refines earlier results from Calc. Var. 52 (2015) and Ann. Global Anal. Geom. 54 (2018) by adapting the inequality and compactness arguments to the fractional setting.

Significance. If the result holds, the work is significant for extending constrained Trudinger-Moser theory to fractional dimensions, where the refined constraint aids in obtaining compactness via an adapted profile decomposition. The self-contained proof using carefully modified concentration-compactness tools, without reduction to classical cases, strengthens the contribution and supports applications to fractional PDEs.

minor comments (2)
  1. [Introduction] In the introduction, the precise range of the fractional dimension parameter could be stated explicitly when comparing to the cited works in Calc. Var. 52 (2015) and Ann. Global Anal. Geom. 54 (2018).
  2. [Preliminaries] Notation for the Orlicz space and the refined constraint should be introduced with a dedicated preliminary subsection to improve readability for readers unfamiliar with the fractional setting.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for the positive assessment of our manuscript and the recommendation to accept it. We appreciate the recognition of the significance of extending the constrained Trudinger-Moser theory to fractional dimensions.

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper derives the Trudinger-Moser inequality under the refined Tintarev-type constraint in fractional dimensions via a profile decomposition adapted to the constraint, combined with standard fractional Sobolev embeddings into Orlicz spaces and compactness arguments. These steps rely on modified concentration-compactness tools that are independent of the target result and do not reduce by construction to fitted inputs, self-definitions, or load-bearing self-citations. The cited prior works (Calc. Var. 52 (2015) and Ann. Global Anal. Geom. 54 (2018)) are external references whose results are refined rather than presupposed as uniqueness theorems or ansatzes from the same authors. The central existence of maximizers follows from the variational analysis without circular reduction.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Assessment limited to abstract; no explicit free parameters, invented entities, or non-standard axioms are mentioned. The result rests on standard functional-analytic assumptions for fractional Sobolev spaces.

axioms (1)
  • domain assumption Fractional Sobolev spaces satisfy the embeddings and compactness properties needed for the variational problem
    Invoked implicitly to guarantee existence of maximizers in the critical regime.

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