ๅ็ธๅๅ
homeomorphism
ๅๅ$ f: U \rightarrow Vใๆฌกใฎๆกไปถใๆบใใๆใfใฏๅ็ธๅๅใจใใ
ๅๅ$ f: U \rightarrow Vใใๅๅ$ f^{-1}: V \rightarrow Uใใๅ
ฑใซ้ฃ็ถๅๅ UใจVใฎ้ใซๅ็ธๅๅ$ f: U \rightarrow VใใใๆใUใจVใฏไบใใซไฝ็ธๅๅใจใใ ๅ็ธๅๅ