Ready.
The figure is a time chart and says that when two processes are running concurrently, they may overlap in time. The figure is trivial. Yet, the consequences, as discussed on other pages, breaks the naive verification algorithm which copycat82 assumes would work. As a result, the intention, obviously, was not to tell the situation, before doing something about it. Only telling it, filling a page, and more. Then, completely ignores its side-effects.