Recognition: no theorem link
It\^o integral for a two-sided L\'evy process
Pith reviewed 2026-05-13 03:34 UTC · model grok-4.3
The pith
An Itô integral is constructed for two-sided finite-variance Lévy processes and shown to extend the Hitsuda-Skorohod integral.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We construct an Itô integral for the two-sided finite-variance Lévy process {L(x)}x∈R without Gaussian component by approximating it with discrete-time martingales and invoking Rosenthal's inequality to bound the p-th moment for even p≥2. Poisson-Malliavin calculus is then applied to establish that the resulting integral is an extension of the Hitsuda-Skorohod integral with respect to the compensated Poisson random measure associated with L.
What carries the argument
The Itô integral obtained via discrete martingale approximation of the two-sided Lévy process, whose moment bounds are derived from Rosenthal's inequality and whose equivalence to the Hitsuda-Skorohod integral is verified through Poisson-Malliavin calculus.
If this is right
- The integral satisfies explicit L^p bounds for every even integer p at least 2.
- The integral can be substituted for the Hitsuda-Skorohod integral when working with the compensated Poisson measure of the Lévy process.
- Stochastic integrals against two-sided Lévy processes become available for use in stochastic differential equations.
Where Pith is reading between the lines
- The construction may allow well-posedness results for SDEs driven by two-sided Lévy processes to be proved by standard fixed-point arguments.
- Similar approximation techniques could be tested on two-sided processes with infinite variance once suitable moment inequalities replace Rosenthal's inequality.
- The two-sided setting might connect to integration theories already developed for processes indexed by the whole real line in other contexts such as random fields.
Load-bearing premise
The two-sided Lévy process admits an approximation by discrete-time martingales to which Rosenthal's inequality applies directly, and the Poisson-Malliavin calculus framework extends to the two-sided case without new technical obstructions.
What would settle it
An explicit two-sided finite-variance Lévy process (for example a compensated compound Poisson process with symmetric jumps) for which the p-moment bound obtained from the discrete approximation fails to hold in the limit, or for which the constructed integral differs from the Hitsuda-Skorohod integral.
read the original abstract
In this article, we construct an It\^o integral with respect to a two-sided finite-variance L\'evy process $\{L(x)\}_{x\in \mathbb{R}}$, without a Gaussian component. Using Rosenthal inequality for discrete-time martingales, we give an estimate for the $p$-th moment of this integral, for any even integer $p\geq 2$. Then, using Poisson-Malliavin calculus, we show that the It\^o integral is an extension of the Hitsuda-Skorohod integral with respect to the compensated Poisson random measure associated to the L\'evy process.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript constructs an Itô integral with respect to a two-sided finite-variance Lévy process without a Gaussian component. It derives p-moment bounds for even p ≥ 2 by applying Rosenthal's inequality to discrete-time martingale approximations of the integral, and then uses Poisson-Malliavin calculus to identify the constructed integral as an extension of the Hitsuda-Skorohod integral with respect to the compensated Poisson random measure associated to the Lévy process.
Significance. If the constructions hold, the work extends stochastic integration theory to two-sided Lévy processes, which is relevant for symmetric jump models in applications. The explicit moment bounds via Rosenthal's inequality and the link to the Hitsuda-Skorohod integral via Malliavin calculus supply concrete tools for further analysis. The paper's direct adaptation of standard one-sided techniques to the two-sided setting is a strength. The stress-test concern about discrete-time martingale approximations and carry-over of the Poisson-Malliavin framework does not appear to land as a load-bearing issue; the manuscript handles the two-sided case without introducing internal inconsistencies or unsupported steps.
minor comments (3)
- [Abstract] Abstract: the statement that the Itô integral 'is an extension' of the Hitsuda-Skorohod integral would be clearer if it specified the precise sense of extension (e.g., agreement on a dense class of integrands) and referenced the relevant theorem number in the main text.
- [Section 1] Section 1 (Introduction): a brief paragraph contrasting the two-sided construction with the standard one-sided Lévy-Itô integral (e.g., differences in the filtration or compensator) would help readers assess the technical novelty.
- [Preliminaries] The notation for the two-sided process L(x), x ∈ ℝ, and its associated random measure should be introduced with an explicit display equation early in the preliminaries to avoid ambiguity when the integral is defined.
Simulated Author's Rebuttal
We thank the referee for the positive and constructive report. The referee correctly summarizes the main contributions of the paper: the construction of the Itô integral for two-sided finite-variance Lévy processes without a Gaussian component, the p-moment bounds obtained via Rosenthal's inequality applied to discrete-time martingale approximations, and the identification with the Hitsuda-Skorohod integral through Poisson-Malliavin calculus. We are pleased that the referee finds the adaptation of one-sided techniques to the two-sided setting free of internal inconsistencies and that the potential concerns regarding the discrete-time approximations and the carry-over of the Poisson-Malliavin framework do not raise load-bearing issues.
Circularity Check
No significant circularity detected
full rationale
The derivation constructs the Itô integral for the two-sided Lévy process via direct approximation by discrete-time martingales (to which Rosenthal's inequality is applied for p-moment bounds) followed by identification with the Hitsuda-Skorohod integral through Poisson-Malliavin calculus. These steps invoke standard external tools without any reduction to self-definitional equations, fitted parameters renamed as predictions, or load-bearing self-citations whose validity depends on the present work. The abstract and described chain remain self-contained against external benchmarks, with no quoted equations or definitions exhibiting the enumerated circular patterns.
Axiom & Free-Parameter Ledger
axioms (3)
- domain assumption The two-sided Lévy process has finite variance and no Gaussian component
- standard math Rosenthal inequality for discrete-time martingales applies to the approximating sums
- domain assumption Poisson-Malliavin calculus extends without obstruction to the compensated Poisson measure of the two-sided process
Reference graph
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discussion (0)
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