It is about the problem of untying knots. For many complex knots it is not know what is the minimal number of steps that are needed to unty it. There was this idea that if a complex knot consisted of two knots for which it is known, that the number would be equal to the sum of the number of steps of the two knots. The article shows that that is not true by showing an example of a knot where the number is one less. This shows that there is no easy route for finding the number for ever larger knots.