what is the proper kernel? why are the kernels that are used in this example proper what is proper kernel x1,x2 how to find which formula is proper how do you determine which kernel is proper what is the proper kernel which of the following formulae defines proper kernels? what are proper kernels which of the following formulae defines proper kernels? why is k a proper kernel which of following formulae defines proper kernels what is proper kernel why are the kernels in k4 correct which formula is appropriate for kernels what statement defines proper kernel which of the following formulae defines proper kernels? why are the following kernels and how to deduce that they are? k4(x1,x2) is _________. which formula defines proper kernel why are kernels proper