Hi,
not being used to work with Maple, I cannot figure out how to solve the following problem.

I want to verify if the positive semidefiniteness of a given 20x20 matrix A (depending on 10 real variables x_1, ..., x_10) implies the positive semidefiniteness of another 4x4 matrix B (depending on the same 10 variables). The entries of each matrix are linear in the given variables, at most depending on 3 variables. The 20x20 matrix is rather sparse.

What I tried is the following: