> Is it related how border maps can all be colored with only four colors?
Actually, that's not generally true. Michigan, for example, violates the axioms behind the four color theorem -- if regions are allowed to have multiple disconnected pieces, a map could theoretically require arbitrarily many colors. For a more pathological example, consider that US embassies are considered "US soil" in an island of their host nation. I'm rather curious about the chromatic number (that is, the smallest number of colors required) of the world map under that consideration.
Embassies are not considered to be foreign territory. The host country gives special privileges to the guest country in accordance with the Vienna Convention.
But there can be an enclave of one country inside another (first-order enclave), as well as enclaves inside enclaves. Dahala Khagrabari was a third-order enclave, an enclave of India inside an enclave of Bangladesh inside an enclave of India in mainland Bangladesh. It was ceded to Bangladesh seven years ago as part of a border gore cleanup treaty.
I used to date somebody who lived across from the Kenyan embassy in DC. The embassy had a few designated parking spaces, but only until 6:30 PM -- about the time I might arrive for a date.
I liked to think that I was parking in Kenyan territory. I was not, for numerous reasons, but it made me happy anyway. Just be out by 6:30 AM.
(It didn't become Kenya again until 9, but it was a travel lane during rush hour. That's why the spot was always open: the signs were so confusing that nobody wanted to park there first.)
Actually, that's not generally true. Michigan, for example, violates the axioms behind the four color theorem -- if regions are allowed to have multiple disconnected pieces, a map could theoretically require arbitrarily many colors. For a more pathological example, consider that US embassies are considered "US soil" in an island of their host nation. I'm rather curious about the chromatic number (that is, the smallest number of colors required) of the world map under that consideration.