>>410
>(M^f)^fが内点を持たないこと
intM,extM:open
X-intM-extM=∂M:closed
∂∂M⊂(∂∂M)∪(∂M)=cl(∂M)=∂M
int∂∂M⊂int∂M
int∂∂M=(∂∂M)∩(int∂∂M)⊂(∂∂M)∩(int∂M)=(∂∂M)∩(∂M-∂∂M)=φ