English has many instances where something is left out because it will be obvious to the reader (who puts it back in again). As an example
...the date Office Building becomes available for lease.
There is an implied "that" as relative pronoun between date and Office Building. It could be written
...the date that the Office Building becomes available for lease.
but this would be wordy and boring.
The pattern recognition for this case looks like (the noun/EndNoun combination created an EndStartNounPhrase)
STRUCTURE1(InsertSymbol,{INSERTMARKER(EndStartNounPhrase, ImpliedRelativePronoun), EndNounPhrase, NOCONNECT(ActiveVerbPhrase)})
The parse chain is cut and the ImpliedRelativePronoun is inserted. It then provides a pivot for the following clause.
....the earlier to occur of..... - implied one
If the tank is empty of fuel the car stops - implied then