"They are looking for a house with three rooms."
Translation:Onlar üç odalı bir ev arıyorlar.
You're correct in your observations, but not in your assumptions about them. "Aramak" is regular, so there will be more vowels disappearing in your future. :-)
The disappearing "A" actually results specifically from the present continuous tense (the -iyor suffix) and the fact that the innocent looking "i" at the front is insanely gluttonous and will eat any vowel it can get its greedy little hands on. He is consonant-intolerant, haha! Here's what happens:
When we remove -mek/-mak from an infinitive verb to start conjugating and the stem ends in a vowel, this final vowel will disappear and the "-i" will harmonize with the NEW final vowel!
- aramak: ara (stem) + iyor = arıyor
- ödemek: öde + iyor = ödüyor
If there is no vowel left in the stem, -iyor will just hang out in the buff, like it was in charge the whole time:
- yemek: ye + iyor = yiyor
It's true that -iyor's evil ways are sometimes hard to notice because some vowels (i, ı, u, ü) are options in the 4-way vowel-harmony game, so we end up replacing the vowel with the same thing we took out.... But if we think about it, we're not doubling or buffering vowels, so the original stem vowel is actually missing (just like the second A in "ara"):
- okumak: oku (root) + iyor = okuyor (NOT okuuyor, okuyuyor, etc.)
And finally, if we look a bit closer at your example in the negative "aramıyor" we can see that this crazy -iyor suffix even stole the vowel off the negative particle!
- ara + ma + iyor = aramıyor
(Sneaky -iyor strikes again! How DOES that little i stay so thin??)
So, the bad news: no vowel is safe before -iyor. But the good news: to my knowledge, this is the only cannibalistic suffix we have to worry about and all the others will be much better behaved! :-)
That would mean: "They are looking, with three rooms, for a house" so it wouldn't work. In Turkish, the verb should always correspond (go side-by-side) with the noun you're using next to it. In this case, "ev" (house). Bir is also necessary because you're sentence has the number 3 (whenever there is a quantity or adjective in the sentence, you must write "bir" as it is no longer optional).