% file is s23.tex
BOUND 2 -  Optimization Over Sphere\\
\[
 q_u(y) :=    y^t(Q-\diag(u))y+u^te+c^ty,
\]
the second relaxed problem
\[
  ~~(RP^2_u)~~~f_2(u) := \max_{||y||^2=n} q_u(y).
\]
Now a  bound for (P) is
\[
  B_2 := \min_{u^te=0} f_2(u) = \min_{u} f_2(u).
\]