Apparatus and methods for organizing data items by directed acyclic graphs

摘要

A data structure for storing items of information having a time of validity includes a validity interval for each item of information, and methods for making and using the same. The items of information are organized in a data structure having nodes and edges connecting the nodes. This data structure is preferably a directed acyclic graph structure. The data structure includes parent nodes and child nodes. The validity interval specified for any child node generally is contained within the validity interval specified for that child node's parent node, such that the data structure includes no child nodes with a validity interval that falls outside of the validity interval of its parent node.