Since there've been several questions about how Judo matches are scored, I thought I'd post this little summary for the curious:
Ippon: Full point - Wins the match immediately.
Waza-ari: Half point - 2 waza-ari's win a match. In addition, even a single waza-ari outweighs any number of yuko or koka and can win a match that ends for time limit.
Yuko: sometimes translated as 'quarter point' - yuko in fact has no true mathematical value. It's worth less than a waza-ari, and outweighs any number of koka. At no point can a player receiving only yuko points win a match against someone who has a waza-ari.
Koka: The lowest value point in a round. At no point can a player receiving only koka points win a match against someone who has yuko or waza-ari.
Rounds scoring a single waza-ari, or only yuko and/or koka go to the time limit, and the player with the most higher-value points wins the match. (ie. 1 yuko beats 6 koka, or 3 yuko beats 2 yuko)
For more information on how each of these points can be scored, as well as penalties, I suggest the following link:
http://www.judo.soc.usyd.edu.au/parts.htm
