Chromatic Homotopy Theory
《Chromatic Homotopy Theory》 · 第 349 页 · Section 11.2.4，Prime knots
There is an operation on knots in \(S^3\) called connected sum, similar to the one on manifolds and described in Figure 11.3. A connected sum is trivial if one of the two knots is trivial; a non-trivial knot is prime if it is not the result of a non-trivial connected sum, and composite otherwise.