Abstract: A method of generating search trees (25, 27) indicating next valid characters for an input interface of a navigation device includes determining a search sub-tree (29) which indicates next valid characters for both a subset of a first set of character strings and for a different second set of character strings. A first search tree (25) is generated based on information on the first set of character strings, and a second search tree (27) is generated based on information on the second set of character strings. The first search tree (25) is generated such that a node (26) of the first search tree (25) references the search sub-tree (29). The second search tree (27) is generated such that another node (28) of the second search tree (27) references the search sub-tree (29).

Abstract: A method for generating a compressed navigation map database from uncompressed navigation map data, wherein the uncompressed navigation map data contains different building blocks of navigation data, each building block addressing a functional aspect of the navigation data, each block containing strings of data. The method includes determining, for each block of the uncompressed navigation map data, most frequent substrings of the block; storing, for each block, the determined most frequent substrings of the block in a seed block; replacing, for each block, in the strings the determined most frequent substrings stored in the seed block by a reference to the seed block thereby generating a compressed block for each block; and storing, for each block, the compressed block and the seed block in order to generate the compressed navigation map database.

Abstract: To update a database of a navigation device which stores at least a base version of a digital map, versions of the digital map which are available locally in the database or remotely from the navigation device are identified. To execute the navigation task, a version of the digital map is selected for execution of the navigation task. Data from a sub-set of storage blocks in which the selected version is stored is required to execute the navigation task. Depending on whether all storage blocks of the sub-set are already stored locally in the database, data stored in storage blocks of the sub-set which are not yet stored locally in the database are downloaded via a wireless interface. The downloaded data are stored in the database without modifying the base version of the digital map.

Abstract: A method of generating search trees (25, 27) indicating next valid characters for an input interface of a navigation device includes determining a search sub-tree (29) which indicates next valid characters for both a subset of a first set of character strings and for a different second set of character strings. A first search tree (25) is generated based on information on the first set of character strings, and a second search tree (27) is generated based on information on the second set of character strings. The first search tree (25) is generated such that a node (26) of the first search tree (25) references the search sub-tree (29). The second search tree (27) is generated such that another node (28) of the second search tree (27) references the search sub-tree (29).

Abstract: A method for generating a compressed navigation map database from uncompressed navigation map data, wherein the uncompressed navigation map data contains different building blocks of navigation data, each building block addressing a functional aspect of the navigation data, each block containing strings of data. The method includes determining, for each block of the uncompressed navigation map data, most frequent substrings of the block; storing, for each block, the determined most frequent substrings of the block in a seed block; replacing, for each block, in the strings the determined most frequent substrings stored in the seed block by a reference to the seed block thereby generating a compressed block for each block; and storing, for each block, the compressed block and the seed block in order to generate the compressed navigation map database.

Abstract: To update a database of a navigation device which stores at least a base version of a digital map, versions of the digital map which are available locally in the database or remotely from the navigation device are identified. To execute the navigation task, a version of the digital map is selected for execution of the navigation task. Data from a sub-set of storage blocks in which the selected version is stored is required to execute the navigation task. Depending on whether all storage blocks of the sub-set are already stored locally in the database, data stored in storage blocks of the sub-set which are not yet stored locally in the database are downloaded via a wireless interface. The downloaded data are stored in the database without modifying the base version of the digital map.

Abstract: A method for assisting a vehicle user in locating a vehicle when parked includes detecting via a mobile device that the vehicle has been placed in a parked state and, in response to detecting that the vehicle has been placed in a parked state, automatically retrieving the vehicle location to the mobile device and recording the vehicle location on the mobile device. The method further entails providing, in response to a request from the user to locate the parked vehicle, instructions to the user to guide the user to the parked vehicle.