"See that moving sidewalk? Why don't you run on it, and then when you reach the end turn back and run to where you started from? I meanwhile will run the same path, but right next to it rather than on it."
Yonette thought about it and said:
"But I don't see the point... We both run with the same speed, and it's the same distance. Sure, I will gain a bit on you while the sidewalk increases my speed, but then I will just lose the advantage while I'm running back and we will arrive at the same time."
Assuming Xavier and Yonette do run with the same speed, who will win the race?