What is the proof of lemma 4.3 in this paper?
That is, how does it follow from 4.1 and 4.2?
Also, why is the constant 8 necessary? How is it used in a way that 1 wouldn't be enough?
There's an LNCS version too, but it also doesn't spell out the proof. There are slides, but they don't seem to be stand-alone: