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An edge list is a data structure used to represent a graph as a list of its edges. An (unweighted) edge is defined by its start and end vertex, so each edge may be represented by two numbers. [1] The entire edge list may be represented as a two-column matrix. [2] [3] An edge list may be considered a variation on an adjacency list which is ...
If the edge has a label, it appears on the same line after the endpoint IDs. [3] The graph may be interpreted as a directed or undirected graph. For directed graphs, to specify the concept of bi-directionality in an edge, one may either specify two edges (forward and back) or differentiate the edge by means of a label.
The time complexity of operations in the adjacency list representation can be improved by storing the sets of adjacent vertices in more efficient data structures, such as hash tables or balanced binary search trees (the latter representation requires that vertices are identified by elements of a linearly ordered set, such as integers or ...
An adjacency list representation for a graph associates each vertex in the graph with the collection of its neighbouring vertices or edges. There are many variations of this basic idea, differing in the details of how they implement the association between vertices and collections, in how they implement the collections, in whether they include both vertices and edges or only vertices as first ...
A hypergraph homomorphism is a map from the vertex set of one hypergraph to another such that each edge maps to one other edge. A hypergraph H = ( X , E ) {\displaystyle H=(X,E)} is isomorphic to a hypergraph G = ( Y , F ) {\displaystyle G=(Y,F)} , written as H ≃ G {\displaystyle H\simeq G} if there exists a bijection
A relational database would first find all the users in "311", extract a list of the primary keys, perform another search for any records in the email table with those primary keys, and link the matching records together. For these types of common operations, graph databases would theoretically be faster. [20]
The nested set model is a technique for representing nested set collections (also known as trees or hierarchies) in relational databases.. It is based on Nested Intervals, that "are immune to hierarchy reorganization problem, and allow answering ancestor path hierarchical queries algorithmically — without accessing the stored hierarchy relation".
It serves adjacency queries in constant time with little storage overhead. This rich form of specifying an unstructured grid is in contrast to simpler specifications of polygon meshes such as a node and element list, or the implied connectivity of a regular grid. An alternative to the winged edge data structure is the Half-edge data structure.