Size and enclosure define it, not ownership. A 4×4 handbreadth space with 10-handbreadth walls is private regardless of who owns it.
Question 2
What is a karmelit?
Karmelit is the middle category — not public enough for Torah liability, not enclosed enough to be private. It has rabbinic restrictions but no Torah-level carrying prohibition.
Question 3
A column in the public domain is 10 handbreadths high and 4×4 handbreadths on top. What is the status of its top surface?
Even in the middle of a public domain, if a surface is 10 handbreadths high and 4×4 wide, its top is halachically a private domain.
Question 4
What is a makom patur?
Makom patur: exempt space. Under 4×4 handbreadths, or above 10 handbreadths in a public domain. You can transfer to/from it freely — extremely useful for complex domain questions.
Question 5
Can you transfer an object from a karmelit to a private domain?
Karmelit has rabbinic restrictions — transfers to/from are forbidden by the Sages. But unlike true public-to-private transfers, there's no Torah-level punishment.