theorem :: CONVEX4:67

for V being non empty Abelian add-associative vector-distributive scalar-distributive scalar-associative scalar-unital CLSStruct
for M1, M2, M3 being Subset of V
for z1, z2, z3 being Complex st M1 is convex & M2 is convex & M3 is convex holds
((z1 * M1) + (z2 * M2)) + (z3 * M3) is convex