Technologies in Minority Report autonomously; in one scene the police remotely override the vehicle in order to bring him into custody. Spielberg commissioned Lexus to design a car specifically for Minority Report, resulting in the Lexus 2054, a fuel-cell powered autonomous vehicle which is seen being built in an automated factory in the film. Autonomous, or self-driving cars have been in development since 1984. As Artificial Intelligence and ground-sensing technologies like LIDAR began to improve in the 2000's, major automotive manufacturers such as Ford, Nissan and General Motors began developing self-driving prototypes. Google began developing a self-driving vehicle prototype, named Waymo in 2009 while
Directed set this article) assume that a directed set is directed upward, unless otherwise stated. Beware that other authors call a set directed if and only if it is directed both upward and downward. Directed sets are a generalization of nonempty totally ordered sets. That is, all totally ordered sets are directed sets (contrast "partially" ordered sets, which need not be directed). Join semilattices (which are partially ordered sets) are directed sets as well, but not conversely. Likewise, lattices are directed sets both upward and downward. In topology, directed sets are used to define nets, which generalize sequences and unite the various