Formula 1 Championship part one

Alonso is the only one who can win the championship in Brazil. Button is the only one whose hopes hang by a fraying thread.
If Button finishes below second in this race, he is definitely out of the running. If he finishes second and Alonso gets any points at all, or Webber gets a win, he is out. If he wins and Alonso gets more than 7 points in this race then he is out.
Under the old points system, this championship would be closer. Under a 'medals' system, which is effectively what is used when points are equal, Button would already be out.
He might think he's still got a chance, but under the current system and after a bad performance in wet conditions that he is supposed to prefer in Yeongam, I can't see it.

Everyone else should be able to continue to challenge for the title in Abu Dhabi next weekend, so long as Webber doesn't finish too low:
A win for Alonso gets him 256 points. If Webber comes second he will have 238, which is one second place off Alonso's total. If he comes third he will have 235, or fourth would give 232, which means he'd need to win the next race and have Alonso do very badly indeed. A fifth place with Alonso winning puts Webber out of the running, and even if Hamilton comes second he will be too far off Alonso to challenge.
If Alonso comes second, he will have 249 points, and it gets more complicated as Hamilton's result will affect whether he can win the championship as well as Webber's. In this situation, a win for Vettel keeps him in the running.
Realistically, Vettel has a good chance of winning both races. Red Bull lock out the front row in most of them. However, the Red Bulls have been plagued with problems, with five race retirements to Ferrari's two. The only other team with less are Mercedes.

Outside the top five, what else is going on? Williams and Force India are three points apart in the constructors championship, on 65 and 68 respectively, and the only teams who can really challenge each other. Although Force India had a better start to the season, Williams have been catching up. Apart from that, if we have a horrible race for crashing out then the new teams are still fighting for places and that elusive point.