Definition:  qualifies n vectors ${U}_{1}\text{,}\text{\hspace{0.17em}}{U}_{2}\text{,}\text{\hspace{0.17em}}\mathrm{...}\text{,}\text{\hspace{0.17em}}{U}_{n}$ where a linear combination such as ${\alpha}_{1}{U}_{1}+{\alpha}_{2}{U}_{2}+\mathrm{...}+{\alpha}_{n}{U}_{n}$ can be equal to zero even if not all scalar coefficients ${\alpha}_{\text{1}}\text{,}\text{\hspace{0.17em}}{\alpha}_{\text{2}}\text{,}\text{\hspace{0.17em}}\cdots \text{,}\text{\hspace{0.17em}}{\alpha}_{n}$ are equal to zero
