| 摘要 |
Object transportation networks may comprise a network of nodes joined by paths in which transportation means may transport objects between the nodes of the network. In some networks, objects are not actively tracked, and thus may only be detected at specific points (such as entries or exits) In such networks we may be interested in knowing whether it is feasible for an object at one location to be transported to another location within a given time frame. In some circumstances we may have a location of interest and time period of interest. We may then be interested in knowing for other locations in the network, the time period during which it was possible to be transported to the location interest during the time period of interest. We may also be interested in knowing the time period during which it was possible to have been at the location of interest during the time point of interest, and have then been transported to another time location in the network. In some cases we may be interested in whether it is possible to have been at the location of interest for the entire duration of the time period of interest. If we have information on locations and times of objects in the network (such as entry location, entry time, and exit location and exit time) then we can further determine which objects could have been at the location of interest during the time period of interest. Various methods are described for performing such queries, and systems for implementing the methods are discussed.
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