The persistence level of a participant with life span life and qualities q in an event with
run time run, by Grimm's descriptions: a participant existing at neither end does not persist,
one existing only at the beginning or only at the end persists existentially there, and one
existing at both ends persists totally or only at the beginning as its qualities are unchanged or
not (Grimm 2011 pp. 524–525).
The definition is too large to print here; read it in the source.
Used by ofLifespan_eq_totalNonPersistence_iff, ofLifespan_eq_exPersEnd_iff, ofLifespan_eq_exPersBeginning_iff, ofLifespan_eq_quPersBeginning_iff, ofLifespan_eq_totalPersistence_iff, exPersBeginning_le_ofLifespan_iff, fst_lt_of_ofLifespan_eq_exPersEnd, not_preExists_of_ofLifespan_eq_exPersEnd, snd_lt_of_ofLifespan_eq_exPersBeginning
Used in Grimm2011