$\left\{ {\begin{aligned} & {{y_j} - \left\langle {\omega ,x} \right\rangle - b \leqslant \varepsilon + {\xi _j}}, \\ & {\left\langle {\omega ,x} \right\rangle - {y_j} + b \leqslant \varepsilon + \xi _j^*}, \\ &{{\xi _j},\xi _j^* \geqslant 0} . \end{aligned}} \right.$ | (3) |