I am puzzled about this simple case,
Suppose we have (A+B)T(A+B) <= (A+B1)T(A+B1),
Can we say something about the relation between BTB and B1TB1?
For example, is it correct if I say BTB <= B1TB1?
Suppose B = {b1,...,bn} and C={c1,...,cn} both are basis set for space V.
D = {d1,...,dn} is basis for space T.
If B and D is linearly independent, is C and D always independent too? How can we prove (disprove) it?