I've often wondered about the way the AI determines which tile to expand a city to, especially later in the game. For instance, in the early game it usually has the sense to push for a lux or strategic in the second or third ring but later on seems to ignore (say) oil, which can be frustrating if it is fourth ring or higher and you can't buy the tile. Is it influenced by the city designation you have selected (i.e. science, gold etc.)? Whilst I'm asking noob questions: how does a Civ that lost it's capital determine which other city to make the capital? Is it most populated or some other value matrix?