Positive-definite kernel
GENERALIZATION OF A POSITIVE-DEFINITE MATRIX
Kernel function; Positive definite kernel; Positive-definite kernel function
In operator theory, a branch of mathematics, a positive-definite kernel is a generalization of a positive-definite function or a positive-definite matrix. It was first introduced by James Mercer in the early 20th century, in the context of solving integral operator equations.