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Badr Elmansouri

Publications and source records attributed to Badr Elmansouri.

11 recordsLinked to original sources

Generalized reflected BSDEs with irregular obstacles driven by RCLL increasing processes on general filtered space

We study generalized backward stochastic differential equations (GBSDEs) and generalized reflected backward stochastic differential equations (GRBSDEs) on a general filtered probability space satisfying the usual conditions, without assuming that the underlying filtration is quasi-left-continuous. The equations are driven by a prescribed predictable, bounded, nondecreasing RCLL process \(A\), which acts as a possibly discontinuous stochastic clock, which we call a driver. We first establish a priori estimates, stability, existence, and uniqueness results for GBSDEs whose generator is Lipschitz continuous with respect to the state variable. Since \(A\) may have jumps, the analysis is carried out in weighted spaces defined through the stochastic exponential \(\mathcal{E}(\beta A)\). We then investigate GRBSDEs with an optional regulated lower obstacle. When the generator is independent of the state variable, we develop two complementary approaches. The first relies on a Snell-envelope representation and optimal stopping arguments, while the second is based on a modified penalization procedure adapted to the discontinuities of the right jumps of the obstacle. The general Lipschitz case is subsequently obtained through a fixed-point argument in an appropriate weighted Banach space.

math.PR

Doubly reflected BSDEs driven by Inhomogeneous simple Levy processes: Applications to generalized Dynkin games

We study doubly reflected backward stochastic differential equations with jumps and two completely separated right-continuous with left limits barriers in a filtration generated by an inhomogeneous Levy process. We establish existence and uniqueness results under a stochastic Lipschitz condition on the driver by means of a penalization method. We also prove a comparison principle and present two closely related applications. The first concerns the nonlinear valuation of an American game option in such a Levy market, while the second addresses the associated generalized Dynkin game under nonlinear expectation. Moreover, under suitable semicontinuity assumptions on the barriers, we establish the existence of a saddle point for the game.

math.PR

Well-posedness of reflected BSDEs with default time and irregular barrier: An application to optimal control

We consider a reflected backward stochastic differential equations with default time and an optional barrier in a filtration generated by a one-dimensional Brownian motion and a defaultable process. We suppose that the barrier have trajectories with left and right finite limits. We provide the existence and uniqueness result when the coefficient is scholastic Lipschitz by using a modified penalization method. Under an additional assumption of right-upper semi-continuity along stopping times on the trajectories of the barrier, we characterize the state process for such RBSDEs as the value function of an optimal stopping problem associated with a non-linear $f$-expectation.

math.PR

Multivalued backward stochastic differential equations with jumps and moving boundary

We prove existence and uniqueness for a one-dimensional multivalued backward stochastic differential equation with jumps. The equation involves a time-indexed family of maximal monotone operators $k_t(\cdot)$ associated with increasing functions $k(t,\cdot)$ taking values in $\mathbb{R}_-$ and having domains that are intervals with time-dependent boundaries. Existence is obtained by a penalization method under a Lipschitz condition on the driver in $(y,z)$, a monotonicity condition in the jump parameter $\psi$, square-integrability of the terminal condition and the driver, and local-in-time integrability conditions on $k(\cdot,y)$. We also address the extension to the case where the operators $k_t(\cdot)$ act on unbounded intervals.

math.PR

Reflected generalized BDSDEs driven by non-homogeneous L\'evy processes and obstacle problems for stochastic integro-PDEs with nonlinear Neumann boundary conditions

We consider reflected generalized backward doubly stochastic differential equations driven by a non-homogeneous L\'evy process. Under stochastic conditions on the coefficients, we prove the existence and uniqueness of a solution. Furthermore, we apply these results to obtain a probabilistic representation for the viscosity solutions of an obstacle problem governed by stochastic integro-partial differential equations with a nonlinear Neumann boundary condition.

math.PR

$\mathbb{L}^p$-solutions for Reflected BSDEs with jumps in a general filtration under stochastic Lipschitz coefficients

In this paper, we establish existence and uniqueness of $\mathbb{L}^p$-solutions, for $p \in (1,2)$, to reflected backward stochastic differential equations (RBSDEs) in a general filtration supporting both a Brownian motion and an independent Poisson random measure. Our results are derived under suitable $\mathbb{L}^p$-integrability assumptions on the data and a stochastic Lipschitz condition on the coefficient.

math.PR

Doubly reflected BSDEs with default time under stochastic Lipschitz coefficients: Filtration links and generalized Dynkin games

We study doubly reflected backward stochastic differential equations (DRBSDEs) on a random horizon $T \wedge \tau$ generated by a default time $\tau$ in a progressively enlarged filtration. We work within the change-of-measure framework previously developed for progressive enlargement, under which the reference Brownian motion stopped at the default time remains a Brownian motion in the enlarged filtration. The DRBSDEs are driven by stochastic Lipschitz generators and involve two RCLL completely separated barriers. We first establish existence and uniqueness of solutions in a weighted square-integrable framework, allowing for an additional martingale component orthogonal to the stopped Brownian martingale. We then investigate the relationship between DRBSDEs formulated in the enlarged filtration and related equations in the reference Brownian filtration. Finally, we formulate a nonlinear Dynkin game on the random horizon $T\wedge\tau$ and characterize its value process in terms of the solution of the associated DRBSDE. Under suitable regularity assumptions, we also identify a saddle point through the first hitting times of the lower and upper barriers.

math.PR

$\mathbb{L}^p$-solutions $(1 <p< 2)$ for reflected BSDEs with general jumps and stochastic monotone generators

We consider a one-reflected backward stochastic differential equation with a general RCLL barrier in a filtration that supports a Brownian motion and an independent Poisson random measure. We establish the existence and uniqueness of a solution in $\mathbb{L}^p$ for $p \in (1,2)$. The result is obtained by means of the penalization method, under the assumption that the coefficient is stochastically monotone with respect to the state variable $y$, stochastically Lipschitz with respect to the control variables $(z,u)$, and satisfies suitable linear growth and $p$-integrability conditions.

math.PR

Generalized Reflected BSDEs with RCLL Random Obstacles in a General Filtration

This paper addresses the existence and uniqueness of solutions to Reflected Generalized Backward Stochastic Differential Equations (GRBSDEs) within a general filtration that supports a Brownian motion and an independent integer-valued random measure. Our study focuses on cases where the given data satisfy appropriate $\mathbb{L}^2$-integrability conditions and the coefficients satisfy a monotonicity assumption. Additionally, we establish a connection between the solution and an optimal control problem over the set of stopping times.

math.PR

$\mathbb{L}^p$ $(p>1)$-solutions for BSDEs with jumps and stochastic monotone generator

We study multidimensional discontinuous backward stochastic differential equations in a filtration that supports both a Brownian motion and an independent integer-valued random measure. Under suitable $\mathbb{L}^p$-integrability conditions on the data, we establish the existence and uniqueness of $\mathbb{L}^p$-solutions for both cases: $p \geq 2$ and $p \in (1,2)$. The generator is assumed to be stochastically monotone in the state variable $y$, stochastically Lipschitz in the control variables $(z, u)$, and to satisfy a stochastic linear growth condition, along with an appropriate $\mathbb{L}^p$-integrability requirement.

math.PR

$\mathbb{L}^p$-solution of generalized BSDEs in a general filtration with stochastic monotone coefficients

We study multidimensional generalized backward stochastic differential equations (GBSDEs) within a general filtration that supports a Brownian motion under weak assumptions on the associated data. We establish the existence and uniqueness of solutions in $\mathbb{L}^p$ for $p \in (1,2]$. Our results apply to generators that are stochastic monotone in the $y$-variable, stochastic Lipschitz in the $z$-variable, and satisfy a general stochastic linear growth condition.

math.PR