In knot theory, the Milnor conjecture says that the slice genus of the
It is in a similar vein to the Thom conjecture.
It was first proved by gauge theoretic methods by Peter Kronheimer and Tomasz Mrowka. Jacob Rasmussen later gave a purely combinatorial proof using Khovanov homology, by means of the s-invariant.
References
Milnor conjecture (topology) Wikipedia(Text) CC BY-SA