,
Michelle Döring
,
Nils Morawietz
Creative Commons Attribution 4.0 International license
Given an undirected graph G, the problem of deciding whether G admits a simple and proper time-labeling that makes it temporally connected is known to be NP-hard (Göbel et al., 1991). In this article, we relax this problem and ask whether a given degree sequence can be realized as a temporally connected graph. Our main results are a complete characterization of the feasible cases, and a recognition algorithm that runs in 𝒪(n) time for graphical degree sequences (realized as simple temporal graphs) and in 𝒪(n+m) time for multigraphical degree sequences (realized as non-simple temporal graphs, where the number of time labels on an edge corresponds to the multiplicity of the edge in the multigraph). In fact, these algorithms can be made constructive at essentially no cost. Namely, we give a constructive 𝒪(n+m) time algorithm that outputs, for a given (multi)graphical degree sequence 𝐝, a temporally connected graph whose underlying (multi)graph is a realization of 𝐝, if one exists.
@InProceedings{casteigts_et_al:LIPIcs.ISAAC.2025.17,
author = {Casteigts, Arnaud and D\"{o}ring, Michelle and Morawietz, Nils},
title = {{Realization of Temporally Connected Graphs Based on Degree Sequences}},
booktitle = {36th International Symposium on Algorithms and Computation (ISAAC 2025)},
pages = {17:1--17:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-408-6},
ISSN = {1868-8969},
year = {2025},
volume = {359},
editor = {Chen, Ho-Lin and Hon, Wing-Kai and Tsai, Meng-Tsung},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2025.17},
URN = {urn:nbn:de:0030-drops-249256},
doi = {10.4230/LIPIcs.ISAAC.2025.17},
annote = {Keywords: temporal paths, gossiping, (multi)graphical degree sequences, edge-disjoint spanning trees, linear time algorithms}
}