,
Michael Hoffmann
,
Stephen Kobourov
,
Maria Eleni Pavlidi
,
Alexandra Weinberger
,
Johannes Zink
Creative Commons Attribution 4.0 International license
We introduce and study the weighted book thickness of graphs. A k-page book embedding of a graph G = (V,E) is defined by a spanning cycle C for V (which does not need to be part of G) and a partition E = ⋃_{i=1}^k E_i such that E∩ C ⊆ E₁ and each graph G_i = (V,E_i∪ C), for 1 ≤ i ≤ k, is outerplane with outer cycle C. If e ∈ E_i, we say that e appears on Page i. The classical book thickness of a graph G is the minimum k such that there exists a k-page book embedding of G, that is, the minimum (over all book embeddings of G) achievable maximum page an edge appears on. In contrast, the weighted book thickness is the minimum achievable average page an edge appears on. The embeddings that realize weighted book thickness can differ from those that realize (classical) book thickness. We show that, although every planar graph on at most nine vertices admits a 2-page book embedding realizing its weighted book thickness, already for ten vertices, there is a planar graph for which every realization of its weighted book thickness needs more pages than its book thickness. We prove that there even exists a 2-tree whose weighted book thickness cannot be realized on two pages. On the positive side, we show that for every graph of pathwidth at most two, the weighted book thickness can always be realized by a 2-page book embedding and such an embedding can be found in linear time. Moreover, we prove that it is NP-complete to decide if the weighted book thickness is at most k, for some given integer k.
@InProceedings{forster_et_al:LIPIcs.GD.2026.27,
author = {F\"{o}rster, Henry and Hoffmann, Michael and Kobourov, Stephen and Pavlidi, Maria Eleni and Weinberger, Alexandra and Zink, Johannes},
title = {{Weighted Book Thickness}},
booktitle = {34th International Symposium on Graph Drawing and Network Visualization (GD 2026)},
pages = {27:1--27:21},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-452-9},
ISSN = {1868-8969},
year = {2026},
volume = {396},
editor = {L\"{o}ffler, Maarten and Miksch, Silvia},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.GD.2026.27},
URN = {urn:nbn:de:0030-drops-279228},
doi = {10.4230/LIPIcs.GD.2026.27},
annote = {Keywords: book thickness, linear layouts, 2-trees}
}