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About the Encyclopedia of Graphs


Encyclopedia of Graphs is an online encyclopedia of graph collections aiming to help researchers find and use data about different families of graphs.

It has been created as a part of the ESF funded GReGAS project combining 16 top scientific teams from all over the world trying to develop a coherent theory of graph representations.


Encyclopedia of Graphs was created by Abelium d.o.o., Research & Development as one of the Slovenian project partners.


The creation of the Encyclopedia of Graphs was financed by the Slovenian Research Agency (ARRS) within the EUROCORES Programme EUROGIGA (project GReGAS) of the European Science Foundation. The infrastructure support (maintenance & updates) is also financially supported by the Slovenian Research Agency (research core funding No. I0-0047).

Terms of use

The text, graph data and their properties on this site are licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0) License, where the form of attribution is defined in the References section. The design and other graphics on this site are the property of Abelium d.o.o.

We will try to publish accurate and updated information, but we do not take responsibility for the accuracy of data and information on the site. All visitors use the published data at their own risk.

Means of use

You can search the site by using graph names, Universal Graph Identifier (UGI) or by collection names.

UGI is a string that uniquely identifies a graph and can be used to directly access its properties page.

Graph collection can be further filtered to obtain the relevant graphs, e.g.

bipartite = true "minimum degree" > 3

After the relevant graphs and their properties have been selected, they can be exported either using their data (sparse6 format) or properties (table). Alternatively, you can download also the data of a specific graph.


Graphs are saved in a canonical sparse6 encoding, achieved by using the nauty software package by Brendan McKay. It can be converted to other formats using nauty or the stand-alone program showg ( link ).

Networks are saved in a .net format as described in the Pajek software manual (pages 87-90). The Pajek software is the work of Vladimir Batagelj and Andrej Mrvar.

The properties of graphs and networks are listed in a comma separated list.


We invite you to help us extend the quality of the Encyclopedia. To contribute new collections, please send us their name, description, graph or network data and properties. Graph data should preferably be encoded in the graph6/sparse6 format or alternatively using adjacency lists, adjacency matrices or list of edges. Network data should preferably be encoded in the .net format.


If referring to the site, you should use:

Pisanski, T., Marušič, D., Potočnik, P., Orbanić, A., Horvat, B. & Lukšič, P. The Encyclopedia of Graphs. Available at http://atlas.gregas.eu.

International Standard Serial Number (ISSN): 2335-2825

More info & contact for contributions