Regarding causation, late preemption occurs, when a process (cause) leads to an effect, but a backup-process is also set in motion and would have led to the same effect, if the other process wouldn't have happened.
A popular example for suche a late preemption is the following:
"Suzy and Billy both throw rocks at a bottle. Suzy is slightly quicker, and consequently it is her rock, and not Billy’s, that breaks the bottle. But Billy, though not as fast, is just as accurate: had Suzy not thrown, or had her rock somehow been interrupted mid-flight, Billy’s rock would have broken the bottle moments later." (Paul & Hall 2013, Causation. A User's Guide. p. 99)
But Paul & Hall also present a slightly different example of this situation:
"Billy and Suzy throw rocks, this time not at a bottle, but at a bell. The bell rings twice in rapid succession: the first time as a result of Suzy’s throw, the second time as a result of Billy’s. Nothing deserving the name “preemption” is going on." (Paul & Hall 2013, Causation. A User's Guide. p. 101)
Paul & Hall, on page 99, show following neuron diagram:
Just one page later, they add this diagram:
My questions are: Which of these situations is an instance of late preemption? And is the bottle-situation represented by the 2nd picture? And the bell-situation by the 1st picture? (Unfortunately I am having a hard time comprehending this english text in the mentioned book.)
In case you want to read the related 2-3 pages: The book is easily available via "libgen".