調柑解析への招待(関数の性質を深く理解するために)
《調柑解析への招待(関数の性質を深く理解するために)》 · 第 394 页 · Section 20
For a two-sheeted covering \(\pi:X\to Y\), sending a cube in \(Y\) to the sum of its two lifts defines a chain homomorphism \(C_*(Y)\to C_*(X)\), called the transfer.