Title
Stochastic algorithmic differentiation of (expectations of) discontinuous functions (indicator functions)
Abstract
In this paper, we present a method for the accurate estimation of the derivative (aka. sensitivity) of expectations of functions involving an indicator function by modifying a (stochastic) algorithmic differentiation, replacing the derivative of the indicator function with a suitable operator. We show that we can split this operator into a conditional expectation operator and the density. This allows using different or improved numerical approximation methods for these operators, e.g. regression. The method is an improvement of the approach presented in C.P. Fries [Automatic backward differentiation for American Monte-Carlo algorithms (conditional expectation). Risk, April, 2018; Stochastic automatic differentiation: Automatic differentiation for Monte-Carlo simulations, Quant. Finance 19(6) (2019), pp. 1043-1059]. The finite difference approximation of a partial derivative of a Monte-Carlo integral of a discontinuous function is known to exhibit a high Monte-Carlo error. The issue is evident since the Monte-Carlo approximation of a discontinuous function is just a finite sum of discontinuous functions and as such, not even differentiable. The algorithmic differentiation of a discontinuous function is problematic. A natural approach is to replace the discontinuity by continuous functions. This is equivalent to replacing a path-wise automatic differentiation by a (local) finite difference approximation. The decoupling of the integration of the Dirac delta and the remaining conditional expectation introduced here results in an improvement in terms of variance reduction and implementation design.
Year
DOI
Venue
2018
10.1080/00207160.2021.1883593
INTERNATIONAL JOURNAL OF COMPUTER MATHEMATICS
Keywords
DocType
Volume
Algorithmic differentiation, adjoint automatic differentiation, Monte Carlo simulation, indicator function, object oriented implementation, variance reduction
Journal
99
Issue
ISSN
Citations 
2
0020-7160
0
PageRank 
References 
Authors
0.34
0
1
Name
Order
Citations
PageRank
Christian P. Fries100.68