Teşekkürler! Is there a different implication between the two sentences in Turkish? In English, if a cat is "on" a tree, I imagine a small, dense tree, like a Christmas tree, with the cat climbing on the outside of it. "In" a tree is more like I described previously, with the cat high up on a branch of a tree, like an oak tree.
The same is sometimes true for t, which is softened to d (f.ex. kanat - kanadım). However, this is not always the case (hayat - hayatım, Cumhuriyet, Cumhuriyetim, adalet - adaletim), and I frankly don't know if there is any rule. My impression is that words of Arabic origin are generally not softened (also with other letters, f.ex. hukuk - hukuki). Interestingly, the t-d thing appears in some verbs as well (gitmek - gidiyorum, etmek - ediyorum) but again not in all verbs (tutmak - tutuyorum). As far as I see, this does not apply to any verb with ç, k or p before the mek/mak (açmak - açıyorum, bırakmak - bırakıyorum, öpmek - öpüyorum). But maybe I have forgotten a verb where it applies...
"Ağacın üzerinde bir kedi var." Translation:There is a cat on the tree.
There is a cat in the tree. - Correct London English. The cat can be at any point before the "crown" of the tree until it is too scared to continue & needs rescuing.
"Ağacın içinde bir kedi var."- There is a cat in the tree. Yes the tree may be rotted & the cat in genuinely inside it. Time to get the "chainsaw" out.