Abstract: Road data is stored in hierarchically organized levels. A lower level has detailed representations of road links and junctions. At a globalized level an abstracted representation is derived: a set of elementary junctions is joined to a complex junction on the basis of predetermined coherencies among the elements of the set. This repeats until all complex junctions have been found. All external road links between a border element of a particular set and any element of a particular neighboring set are detected, including allowed traffic directions on the external road links. The links are collected to a single complex road link while mapping the allowed traffic directions thereon. This repeats until all complex road links have been found. Remaining elementary and complex junction are represented by a respective single node. Also, each remaining elementary and complex road link is represented by a single higher level road link.

Abstract: The invention relates to a tunnel diode provided with two metallically conducting electrodes (1, 2) with an insulating dielectric (3) in between, which forms a barrier with a barrier level for electrons and which has a thickness such that electrons can tunnel through the barrier from the one to the other electrode. Such a tunnel diode has the disadvantage that it has no memory. In many applications it is desirable for the tunnel diode to hold a certain switching state, such as open/closed. According to the invention, the tunnel diode is characterized in that the dielectric (3) comprises a layer of a material which is ferroelectric at room temperature with a remanent polarization which influences the barrier level. It is achieved thereby that the tunnel diode has various switching states in dependence on the remanent polarization of the dielectric (3). The switching state is maintained until the polarization of the dielectric (3) changes.