Graphics[ {EdgeForm[Directive[Thin, Black]], Black, Disk[{0, 0}, 1, {0, Pi}], EdgeForm[Directive[Thin, LightGray]], White, Disk[{0, 0}, 1, {Pi, 2 Pi}], EdgeForm[Directive[Thin, Gray]], Black, Disk[{1/2, 0}, 1/2, {Pi, 2 Pi}], White, Disk[{1…