Is it true that under certain conditions, `Mg` can reduce `SiO_(2)`, and `Si` can reduce `MgO` ?

It is true that under certain condition, Mg can reduce Al_2O_3 and Al can reduce MgO ? What are those conditions?

The under certain conditions magnesium can be reduce SiO_(2) and silicon can reduce MgO. What are those conditions?

SO_(2) can reduce :

A can reduce BO_2 under which conditions.