Is it true that under certain conditions, Mg can reduce SiO₂ and Si can reduce MgO? What are those conditions?

The temperature range in which is lesser than, Mg can reduce SiO_{2 to} Si.

On the other hand, the temperatures range in which is less than, Si can reduce MgO to Mg.

The temperature at which Δ_fG curves of these two substances intersect is 1966 K. Thus, at temperatures less than 1966 K, Mg can reduce SiO₂ and above 1966 K, Si can reduce MgO.