They’re not matrices, but a proof of Fermat’s theorem on sums of two squares involves choosing prime p and then parameterizing one of these objects with zero, one, p and a square root of negative one in the field of order p. Point groups of these objects have their degrees limited to one, two, three, four, or six by a “restriction theorem.” (15[2])When a symmetric convex (15[1])bounded subset of R·n (“R N”) does not non-trivially intersect one of these objects, its volume is at most two-to-the-n by Minkowski’s (“min-KOF-skeez”) theorem. Maryna Viazovska (-5[1])proved that optimal sphere packings follow (*) “E-sub-eight” (10[1])and “Leech” examples (10[2])of these (10[1])objects. (10[1])These objects (10[1])can be defined as the integer linear combinations of a basis set of Euclidean space. For 10 points, name these mathematical objects exemplified by one named for Bravais (“brah-VAY”) that is used in crystallography. ■END■