A subgroup of a group can also be defined as another abstract group along with an injective homomorphism (or embedding) from that abstract group to the given group. Here, the other abstract group can be naturally identified via its image under the homomorphism, which is the subgroup in a more literal sense.
For the skate brand of the same name, see Roller Derby (brand). Roller derby is a contact sport played by two teams of five members roller skating in the same direction around a track. Game play consists of a series of short match ups (jams) in which both teams designate a jammer who scores points by lapping members of the opposing team.
1. Kingda Ka, Six Flags Great Adventure, Jackson, NJ, USA - 456 feet. Kingda Ka is the world's tallest roller coaster, and was the world's fastest until Formula Rossa opened in November 2010. The train is launched by a hydraulic launch mechanism to 128 miles per hour in 3.5 seconds.