Solution
= Solution
The general estimate from part 1 and the exact inverse <norm> from part 2b imply
$$
\boxed{\|P_x\|_{L^\infty}\le\|A_x^{-1}\|_{\ell^\infty}<2,}
$$
and in particular \b[$\|P_x\|_{L^\infty}\le2$], uniformly in the number of knots. This bound concerns the <support>-centred sites $x_i=i+3/2$; shifting the sampling sites changes the <B-spline collocation matrix> and can destroy uniform stability.