U ?h3@s4dZddlZddlmZdgZeddddZdS)aGenerators for cographs A cograph is a graph containing no path on four vertices. Cographs or $P_4$-free graphs can be obtained from a single vertex by disjoint union and complementation operations. References ---------- .. [0] D.G. Corneil, H. Lerchs, L.Stewart Burlingham, "Complement reducible graphs", Discrete Applied Mathematics, Volume 3, Issue 3, 1981, Pages 163-174, ISSN 0166-218X. N)py_random_staterandom_cographcs^tdt|D]F}tfdd}|dddkrLt|qt|qS)aReturns a random cograph with $2 ^ n$ nodes. A cograph is a graph containing no path on four vertices. Cographs or $P_4$-free graphs can be obtained from a single vertex by disjoint union and complementation operations. This generator starts off from a single vertex and performs disjoint union and full join operations on itself. The decision on which operation will take place is random. Parameters ---------- n : int The order of the cograph. seed : integer, random_state, or None (default) Indicator of random number generation state. See :ref:`Randomness`. Returns ------- G : A random graph containing no path on four vertices. See Also -------- full_join union References ---------- .. [1] D.G. Corneil, H. Lerchs, L.Stewart Burlingham, "Complement reducible graphs", Discrete Applied Mathematics, Volume 3, Issue 3, 1981, Pages 163-174, ISSN 0166-218X. rcs |tS)N)len)xRN/var/www/html/venv/lib/python3.8/site-packages/networkx/generators/cographs.py;z random_cograph..r)nxZ empty_graphrangeZ relabel_nodescopyrandintZ full_joinZdisjoint_union)nseediZRRr rr rs$  )N)__doc__Znetworkxr Znetworkx.utilsr__all__rr r r r s