"Apparently he is going to the conference that they arranged."
Translation:Anlaşılan onların düzenlediği konferansa gidiyor.
For gerunds, I know the following:
benim düzenlediğim konferans = the conference I organised
senin düzenlediğin konferans = the conference you organised
onun düzenlediği konferans = the conference he/she organised
bizim düzenlediğimiz konferans = the conference we organised
sizin düzenlediğiniz konferans = the conference you organised
In this example, düzenlediği is being used with onlar, which is similar to other verb conjugations where onlar can also use the same suffixes as O.
For onlar, can you say onların düzenledikleri konferans? If so, is there a difference in meaning?
Well, for "düzenlediği", you cannot omit "onların", since if you omit then the meaning is not clear. (You can also put "onun", "Ayse'nin, "kendisinin" etc etc.)
For "düzenledikleri", the meaning is still be vague. The reason is that when you write the sentence without "onların", then for me it is not clear that the group of people who arranged the conference also includes him (the subject) or not.
In short, you cannot omit "onların" in both sentences...
Well, yes and no. The -lAr in "düzenledikleri' has nothing to do with onlar actually. It just makes it plural. "düzenledikleri' can still mean "the things that they/he/she/it arranged"
Correcting myself: Both are fine with onlar. Using the -lAr suffix on the participle doesn't change meaning. It isn't required, and is often dropped. The only issue is when you choose to drop the following object, in which it ought to be plural. Look at us learning together :D
That being said, unless you state onun or onların, it is still vague :D
onlarin is necessary otherwise it could he's going to a conference he has organised. I even put Anlaşılan onların düzenlediği konferansa on gidiyor but it was marked wrong. i also agree with the ones saying we should use the other past, which seems to have been used in the lesson only, you never come across it elsewhere in the course.