Isidor Natanson is a name that might refer to a historical or contemporary figure, but without specific context, it's unclear who exactly is meant. It could refer to a scientist, an artist, or another notable individual, depending on the field or area of interest.

James Mercer is a mathematician best known for his contributions to functional analysis and statistics, particularly in the development of the Mercer theorem. The Mercer theorem provides conditions under which a continuous positive semidefinite kernel can be represented in terms of an infinite series of eigenfunctions. This has important applications in various fields, including machine learning, where it is often used in the context of support vector machines and kernel methods.

Jean-Michel Bony is not a widely recognized figure in popular media or history as of my last knowledge update in October 2021. It’s possible that he could be a professional in a specific field, such as academia, business, or arts, but there isn't much publicly available information about him.

John Edensor Littlewood (1885–1977) was an influential English mathematician known for his contributions to various areas of mathematics, particularly in analysis, number theory, and mathematical logic. He is well-remembered for his collaboration with G.H. Hardy, with whom he co-authored several important works, including the famous "Hardy-Littlewood Method," which involves techniques in analytic number theory.

John Horvath is a mathematician known for his contributions to various areas of mathematics, including functional analysis, partial differential equations, and mathematical logic. His work often involves applied mathematics and theoretical research. Specific details about his birth, education, and major works may not be widely published, but he may be recognized in academic circles for specific contributions to mathematical theory and practice. For more in-depth information about his research and publications, it's best to consult academic databases or his professional profiles on institutional websites.

Jonathan Partington is a mathematician known for his work in the field of mathematics, particularly in analysis and topology. He is also recognized for his contributions to the educational aspect of mathematics, often sharing his insights through lectures, publications, and online resources.

Joseph L. Doob (1910–2004) was an influential American mathematician known primarily for his contributions to the fields of probability theory and stochastic processes. He is renowned for his work on measure theory and for developing concepts that laid the groundwork for modern probability. Among his significant contributions is the formulation of Doob's martingale concept, which has extensive applications in various areas, including financial mathematics, statistics, and mathematical physics.