“A {{w|Knot theory|knot}} is said to be slice if it bounds a {{w|Embedding#Differential topology|smooth properly embedded}} {{w|Disk (mathematics)|disk}} in the {{w|Ball (mathematics)|4-ball}}. We demonstrate that the {{w|Conway knot}}, 11n34 in the Rolfsen tables, is not slice. This completes the classification of slice knots under 13 {{w|Knot theory#Knot diagrams|crossings}}, and gives the first example of a non-slice knot which is both topologically slice and a positive mutant of a slice knot.”