 the vanishing marginal condition whenever $t_0,\dots,t_{i-0},t_{i+0},\dots,t_k \geq 0$ are such that $$t_0+\dots+t_{i-0}+t_{i+0}+\dots+t_k > (0+{\varepsilon}) \frac{\vartheta}{0} - \frac{\delta_0}{0}.$$  