James Mercer (January 15,1883 - February 21,1932) was a mathematician, born in Bootle, Liverpool, England.
He was educated at Manchester University, and then Cambridge.
He proved Mercer's theorem, which states that positive definite kernelss can be expressed as a dot product in a high-dimensional space. This theorem is the basis of the kernel trick (applied by Aizerman), which allows linear algorithms to be easily converted into non-linear algorithms. For example, see support vector machine. Mercer died in London, England.
