What kind of word is this? "случи́вшемся"

Question

Grammatically and morphologically speaking, what kind of word is this? "случи́вшемся" in the following sentence:

Поговори́ с сы́ном о случи́вшемся.

ChatGPT says: The word "случи́вшемся" is a past passive participle in the prepositional case, derived from the verb "случиться," which means "to happen" or "to occur." In the prepositional case, the word can be translated as "about the happened" or "about the occurred (event)."

However I can't tell if the AI is hallucinating, because after reading Wade's " A Comprehensive Russian Grammar" section on Participles, I still can't figure out how this word was derived. Can someone confirm that the AI is correct? Is it past perfective?

Would I then accurately translate it as: "Talk to the son about what has happened."?

Answer 1

Is it past perfective?

It's a past participle from the perfective reflexive verb случиться ("to happen, to occur"), through the suffix -вш- (used to form active past participles), the ending -ем- (masculine prepositional singular) and the reflexive particle -ся (carried from the original verb).

Reflexive verbs can only form active participles, so the model is wrong in this aspect, but otherwise the model's answer is correct.

Answer 2

This is the active past participle случи́вшееся from the verb случиться to happen, which declines like any neuter adjective. Here, it's in the prepositional singular after o and means about what happened.
[Literally: about the occurred].

Answer 3

Your translation is accurate.

Here is how past participles are derived:

The active past participle is derived from the past masculine singular: if the past masculine singular end in -л, replace -л with -вший, otherwise add -ший.

[From Zaliznyak's Grammatical Dictionary of Russian.]

E.g. ел – евший, гулял – гулявший, случился – случившийся.

If the verb ends in -ся, you need to remove it before applying the rule, and then add it back.

Now, случившийся is a participle and it can be declined for gender, number and case like an adjective. To make it agree with the singular neuter оно (it), we change the ending -ий to -ее: случившийся – случившееся (compare to хороший – хорошее). For the prepositional case, the ending is -ем: случившемся.