Signed row sum under a Boolean coloring

For a real-valued row $a:\mathrm{Fin}\,m\to\mathbb R$ (typically with entries in $\{0,1\}$) and a Boolean coloring $\chi$, $\mathrm{rowSumB}(a,\chi)=\sum_{j} a_j\,\mathrm{RSign}(\chi,j)$ is the signed discrepancy of that row under the coloring $\chi$ — the quantity Spencer's theorem bounds.