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Causal Hamilton-Jacobi-Bellman Equations for Anticipative Stochastic Optimal Control

Peter Bank, Franziska Bielert

TL;DR

The paper develops a causal Hamilton-Jacobi-Bellman framework for anticipative stochastic control with rough-path dynamics, where the controller can see the future Brownian motion over a moving horizon. By merging the martingale optimality principle with a pathwise, Dupire-based functional Itô calculus, it derives a deterministic HJB in terms of causal derivatives and a transport term reflecting anticipativity, linking the value function $v$ to a path-dependent map $u$. A verification theorem and a regular-value analysis are provided, leveraging conditional distributions and pathwise quadratic variation to establish both sufficiency and necessity of the HJB under suitable regularity. The approach is illustrated through insider-investment and front-running-style examples, demonstrating how anticipative information can be incorporated into a robust rough-path control framework with concrete HJB characterizations.

Abstract

We consider a stochastic optimal control problem where the controller can anticipate the evolution of the driving noise over some dynamically changing time window. The controlled state dynamics are understood as a rough differential equation. We combine the martingale optimality principle with a functional form of Itô's formula to derive a Hamilton-Jacobi-Bellman (HJB) equation for this problem. This HJB equation is formulated in terms of Dupire's functional derivatives and involves a transport equation arising from the anticipativity of the problem.

Causal Hamilton-Jacobi-Bellman Equations for Anticipative Stochastic Optimal Control

TL;DR

The paper develops a causal Hamilton-Jacobi-Bellman framework for anticipative stochastic control with rough-path dynamics, where the controller can see the future Brownian motion over a moving horizon. By merging the martingale optimality principle with a pathwise, Dupire-based functional Itô calculus, it derives a deterministic HJB in terms of causal derivatives and a transport term reflecting anticipativity, linking the value function to a path-dependent map . A verification theorem and a regular-value analysis are provided, leveraging conditional distributions and pathwise quadratic variation to establish both sufficiency and necessity of the HJB under suitable regularity. The approach is illustrated through insider-investment and front-running-style examples, demonstrating how anticipative information can be incorporated into a robust rough-path control framework with concrete HJB characterizations.

Abstract

We consider a stochastic optimal control problem where the controller can anticipate the evolution of the driving noise over some dynamically changing time window. The controlled state dynamics are understood as a rough differential equation. We combine the martingale optimality principle with a functional form of Itô's formula to derive a Hamilton-Jacobi-Bellman (HJB) equation for this problem. This HJB equation is formulated in terms of Dupire's functional derivatives and involves a transport equation arising from the anticipativity of the problem.

Paper Structure

This paper contains 19 sections, 16 theorems, 223 equations.

Key Result

Theorem 3.4

Let $\mathrm{\mathbf{X}}=(X,\mathbb{X})$ be an $\alpha$-Hölder rough path over $\mathop{\mathrm{\mathbb{R}}}\nolimits^d$ and $(Y,Y')$ be an $(\alpha,\beta)$-Hölder $X$-controlled rough path over $\mathop{\mathrm{\mathbb{R}}}\nolimits^{n\times d}$ such that $\beta\in(0,\alpha]$ and $2\alpha+\beta>1$. is a well-defined limit along partitions $\mathcal{P}$ of $[0,T]$ that we call rough integral. More

Theorems & Definitions (49)

  • Definition 3.1: $\alpha$-Hölder Rough Path
  • Example 3.2: Itô Lift
  • Definition 3.3: $(\alpha, \beta)$-Hölder $X$-controlled Rough Path
  • Theorem 3.4: Rough Integration
  • Theorem 3.5: Existence and Properties of Solutions
  • proof
  • Example 3.6
  • Remark 3.7: Measurability and Random Initial Data
  • Lemma 4.1
  • proof
  • ...and 39 more