for V being ComplexLinearSpace
for M being Subset of V
for z1, z2 being Complex st ex r1, r2 being Real st
( z1 = r1 & z2 = r2 & r1 >= 0 & r2 >= 0 ) & M is convex holds
(z1 * M) + (z2 * M) = (z1 + z2) * M