Petr Kohn’s contributions to mathematical finance, particularly in the realm of partial differential equations (PDEs), have significantly advanced the field. His work centers around developing and analyzing numerical methods for solving complex financial models, contributing to more accurate pricing and hedging of derivatives. Kohn’s research often involves free boundary problems and optimal stopping, both central to understanding derivative valuation under various constraints and uncertainties.
One key area of Kohn’s expertise lies in American option pricing. Unlike European options which can only be exercised at maturity, American options allow holders to exercise at any time before the expiration date. This early exercise feature introduces a free boundary – the optimal exercise boundary – which separates the region where it’s optimal to hold the option from the region where it’s optimal to exercise. Finding this optimal boundary requires solving a PDE subject to certain boundary conditions, a notoriously difficult task. Kohn’s work has provided innovative numerical techniques, including penalty methods and variational inequalities, to approximate this free boundary with high accuracy and efficiency.
Beyond American options, Kohn’s research extends to other complex derivatives, such as path-dependent options (e.g., Asian options, barrier options) and options on multiple assets. These derivatives often require higher-dimensional PDEs, making numerical solutions computationally expensive. Kohn’s work has explored techniques like operator splitting and dimension reduction to mitigate this computational burden, enabling the efficient pricing and hedging of these instruments. He has also contributed to the development of robust numerical schemes that are stable and accurate even when dealing with discontinuous payoffs or volatile market conditions.
Furthermore, Kohn’s work touches upon the crucial topic of model calibration. Financial models, like the Black-Scholes model or more sophisticated stochastic volatility models, rely on parameters that need to be estimated from market data. This calibration process often involves solving inverse problems, which are mathematically challenging. Kohn’s research has explored optimization techniques and regularization methods to improve the stability and accuracy of model calibration, leading to more reliable model predictions.
In essence, Petr Kohn’s work on PDEs in finance provides valuable tools and insights for practitioners and researchers alike. His contributions help to address the computational challenges involved in pricing and hedging complex derivatives, improving risk management practices and fostering greater efficiency in financial markets. His research highlights the critical role of sophisticated mathematical techniques in understanding and navigating the intricacies of modern financial instruments.