Chromatic Homotopy Theory
《Chromatic Homotopy Theory》 · 第 290 页 · Section 9.3.1（本书采用连通可定向曲面的约定）
Throughout all this section \(M\) denotes a compact orientable 3-manifold with (possibly empty) boundary. Let \(S\subset M\) be a properly embedded orientable surface. A compressing disc for \(S\) is a disc \(D\subset M\) with \(\partial D=D\cap S\), such that \(\partial D\) does not bound a disc in \(S\). […] A properly embedded connected orientable compact surface \(S\subset M\) with \(\chi(S)\leq 0\) is compressible if it has a compressing disc, and incompressible otherwise.