% file s26.tex
THEOREM\\
Suppose that $f_4(v) := \max_{-1 \leq x \leq 1} q^c_v(x)$ and
\[B_4 :=
\min_{Q^c-\diag(v) \leq 0} f_4(v).\]
Then
\[ B_1 = B_2 = B_3 = B_4. \]