= Integral norm for weak Lq
{title2=$N_q(f)=\sup_E|E|^{-1/q'}\int_E|f|$}
The integral expression for the <weak Lq space> is homogeneous, positive definite up to equality almost everywhere, and obeys the <triangle inequality> by integrating $|f+g|\leq|f|+|g|$ over each set. Its exponent is $-1/q'$, not $-1/q$. The sharp comparison constant with the distribution-function quasi-norm is $q'$; the power function $x^{-1/q}$ on $(0,\infty)$ attains that ratio on initial intervals.
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