REVIEW 52 references
Weighted book thickness can require more pages than classical book thickness, already for a 10-vertex planar graph and for a 2-tree.
Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →
Weighted book thickness can require strictly more pages than classical book thickness, already for a 10-vertex planar graph and for a 2-tree, but equals the 2-page value for all pathwidth-2 graphs.
T0 review reviewed 2026-07-31 challenge →
load-bearing objection Solid new parameter with clean separations and a linear-time pathwidth-2 algorithm; the 2-tree claim needs a quick cardinality check on the SAT encoding but the rest holds up.
Weighted Book Thickness
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
Core claim
There exist graphs whose weighted book thickness is strictly smaller than their weighted book thickness restricted to bt(G) pages. Concretely, a planar pathwidth-3 graph G on ten vertices satisfies wbt(G)=wbt3(G)=22/19 < wbt2(G)=23/19, and a 2-tree on ninety-nine vertices satisfies wbt3(G)=220/195 < wbt2(G)=221/195; every pathwidth-2 graph, however, satisfies wbt=wbt2 and an optimal two-page embedding is computable in linear time.
What carries the argument
The weighted book thickness wbt(G) is the minimum, over all book embeddings, of the average page index of an edge; the restricted quantity wbt_k(G) forces the embedding to use at most k pages. Separation is proved by exhibiting concrete spine orders and page assignments together with exhaustive outerplanarity and SAT arguments that rule out better averages on fewer pages.
Load-bearing premise
The computer-checked claims for nine-vertex planar graphs and the ninety-nine-vertex 2-tree rest on the correctness of a custom SAT encoding of outerplanarity and page-assignment constraints.
What would settle it
Exhibit either a two-page book embedding of the ten-vertex planar graph whose total page-sum is at most 22, or a two-page embedding of the ninety-nine-vertex 2-tree whose total page-sum is at most 220; either finding would collapse the claimed separations.
If this is right
- For pathwidth-2 graphs the cheapest average is always attained already on two pages and can be computed in linear time.
- Planar graphs on at most nine vertices never need extra pages for the weighted optimum.
- Even 2-trees can force an extra page when the objective switches from maximum to average page number.
- Deciding whether weighted book thickness is at most a given integer is NP-complete for planar triangulations.
Where Pith is reading between the lines
- The same average-versus-maximum gap may appear for other linear layout parameters such as queue number or deque number once analogous weighted variants are defined.
- If the page-cost function grows faster than linear, the gap between the unrestricted weighted optimum and the optimum restricted to bt(G) pages is likely to widen.
- The linear-time pathwidth-2 algorithm suggests that other bounded-pathwidth classes may still admit efficient weighted optima even when classical thickness is hard.
Editorial analysis
A structured set of objections, weighed in public.
Circularity Check
No circularity: weighted book thickness is a fresh definition; separations and algorithms are proved from outerplanarity minors, Whitney uniqueness, path/treewidth structure, and explicit SAT encodings of those constraints.
full rationale
The paper defines wbt and wbt_k from scratch (Section 2) as min average page index over book embeddings, then derives bounds and separations by standard combinatorial arguments: outerplanarity forbidden subdivisions (Theorem 1 / Chartrand–Harary), Whitney uniqueness of 3-connected planar embeddings, known pathwidth characterizations (Barát et al.), and explicit counting of edges forced off Page 1 via K_{2,3}/K_{2,4} subdivisions (Lemmas 9–10). The computer-aided parts (Theorems 6–7) encode precisely those derived missing-edge constraints into an external SAT framework (Bekos–Kaufmann–Zielke variables σ, ϕ, χ) and report UNSAT; the encodings are not fitted to a target ratio, nor do they redefine wbt in terms of itself. NP-completeness is a direct reduction from planar Hamiltonicity. Pathwidth-2 optimality (Theorem 13) constructs a maximum outerplanar subgraph by a linear-time marking procedure and exhibits a separating subhamiltonian cycle. No step equates a claimed prediction to a fitted input or to a self-citation uniqueness theorem. The skeptic’s cardinality remark on Lemma 10 is a possible correctness gap, not a circular reduction. Score 0 is therefore appropriate.
Axiom & Free-Parameter Ledger
axioms (5)
- standard math A graph is outerplanar iff it contains no subdivision of K2,3 or K4 (Chartrand–Harary).
- standard math 3-connected planar graphs have a unique embedding up to reflection (Whitney).
- standard math Biconnected pathwidth-2 graphs consist of two paths P,Q joined by noncrossing chords and length-2 paths (Barát–Hajnal–Lin–Yang).
- standard math Hamiltonicity of planar triangulations is NP-complete (Wigderson).
- domain assumption A graph admits a 2-page book embedding iff it is subhamiltonian.
invented entities (2)
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weighted book thickness wbt(G) / wbt_k(G)
no independent evidence
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sunflower graph S and the 99-vertex 2-tree G built from 12 copies around a triangle
no independent evidence
Cite this review
Pith. "Pith review of Weighted Book Thickness." pith.science (2026). https://pith.science/paper/5FATG7WK
@misc{pith2026260724375,
author = {Pith},
title = {Pith review of: Weighted Book Thickness},
year = {2026},
howpublished = {\url{https://pith.science/paper/5FATG7WK}},
note = {Machine review of arXiv:2607.24375}
}
abstract
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 $E=\bigcup_{i=1}^{k}E_i$ such that $E\cap C\subseteq E_1$ and each graph $G_i=(V,E_i\cup C)$, for $1 \le i \le k$, is outerplane with outer cycle $C$. If $e\in E_i$, 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 $k$.
Reference graph
Works this paper leans on
-
[1]
J. F. Balow. Cost optimization of pipe sewerage systems. Proceedings of the Institution of Civil Engineers , 53(1):57--64, 06 1972. https://doi.org/10.1680/iicep.1972.5576 doi:10.1680/iicep.1972.5576
arXiv 1972
-
[2]
On the structure of graphs with path-width at most two
J \' a nos Bar \' a t, P \' e ter Hajnal, Yixun Lin, and Aifeng Yang. On the structure of graphs with path-width at most two. Studia Scientiarum Mathematicarum Hungarica , 49(2):211--222, 2012. https://doi.org/10.1556/sscmath.49.2012.2.1200 doi:10.1556/sscmath.49.2012.2.1200
-
[3]
Crossing reduction in circular layouts
Michael Baur and Ulrik Brandes. Crossing reduction in circular layouts. In Juraj Hromkovic, Manfred Nagl, and Bernhard Westfechtel, editors, Proc. 30th International Workshop on Graph-Theoretic Concepts in Computer Science (WG 2004) , volume 3353 of Lecture Notes in Computer Science , pages 332--343. Springer, 2004. https://doi.org/10.1007/978-3-540-30559...
-
[4]
Bekos, Stefan Felsner, Philipp Kindermann, Stephen G
Michael A. Bekos, Stefan Felsner, Philipp Kindermann, Stephen G. Kobourov, Jan Kratochv \' l, and Ignaz Rutter. The rique-number of graphs. In Patrizio Angelini and Reinhard von Hanxleden, editors, Proc. 30th International Symposium on Graph Drawing and Network Visualization (GD 2022) , Lecture Notes in Computer Science, pages 371--386. Springer, 2022. ht...
-
[5]
Bekos, Mirco Haug, Michael Kaufmann, and Julia M \" a nnecke
Michael A. Bekos, Mirco Haug, Michael Kaufmann, and Julia M \" a nnecke. An online framework to interact and efficiently compute linear layouts of graphs. CoRR , abs/2003.09642, 2020. https://arxiv.org/abs/2003.09642 arXiv:2003.09642
Pith/arXiv arXiv 2003
-
[6]
Bekos, Michael Kaufmann, Fabian Klute, Sergey Pupyrev, Chrysanthi N
Michael A. Bekos, Michael Kaufmann, Fabian Klute, Sergey Pupyrev, Chrysanthi N. Raftopoulou, and Torsten Ueckerdt. Four pages are indeed necessary for planar graphs. J. Comput. Geom. , 11(1):332--353, 2020. https://doi.org/10.20382/JOCG.V11I1A12 doi:10.20382/JOCG.V11I1A12
-
[7]
Bekos, Michael Kaufmann, Maria Eleni Pavlidi, and Xenia Rieger
Michael A. Bekos, Michael Kaufmann, Maria Eleni Pavlidi, and Xenia Rieger. On the deque and rique numbers of complete and complete bipartite graphs. In Denis Pankratov, editor, Proc. 35th Canadian Conference on Computational Geometry (CCCG 2023) , pages 89--95, 2023. URL: https://wadscccg2023.encs.concordia.ca/assets/pdf/CCCG_2023_proc.pdf
2023
-
[8]
Bekos, Michael Kaufmann, and Christian Zielke
Michael A. Bekos, Michael Kaufmann, and Christian Zielke. The book embedding problem from a SAT -solving perspective. In Emilio Di Giacomo and Anna Lubiw, editors, Proc. 23rd International Symposium on Graph Drawing and Network Visualization (GD 2015) , volume 9411 of LNCS , pages 125--138. Springer, 2015. https://doi.org/10.1007/978-3-319-27261-0 \_11 do...
-
[9]
Frank Bernhart and Paul C. Kainen. The book thickness of a graph. Journal of Combinatorial Theory, Series B , 27(3):320--331, 1979. https://doi.org/10.1016/0095-8956(79)90021-2 doi:10.1016/0095-8956(79)90021-2
-
[10]
T\' o th, and Manuel Wettstein
Jean Cardinal, Michael Hoffmann, Vincent Kusters, Csaba D. T\' o th, and Manuel Wettstein. Arc diagrams, flip distances, and H amiltonian triangulations. In Proc. 32nd International Symposium on Theoretical Aspects of Computer Science (STACS 2015) , volume 30 of Leibniz Internat. Proc. Informatics (LIPIcs) , pages 197--210. Schloss Dagstuhl--Leibniz-Zentr...
-
[11]
T\' o th, and Manuel Wettstein
Jean Cardinal, Michael Hoffmann, Vincent Kusters, Csaba D. T\' o th, and Manuel Wettstein. Arc diagrams, flip distances, and H amiltonian triangulations. Comput. Geom. , 68:206--225, 2018. https://doi.org/10.1016/j.comgeo.2017.06.001 doi:10.1016/j.comgeo.2017.06.001
-
[12]
Planar permutation graphs
Gary Chartrand and Frank Harary. Planar permutation graphs. Annales de l' Institut Henri Poincar \'e - Probabilit \'e s et Statistiques , 3:433--438, 1967. URL: https://eudml.org/doc/76875
1967
-
[13]
Fan R. K. Chung, Frank Thomson Leighton, and Arnold L. Rosenberg. Embedding graphs in books: A layout problem with applications to VLSI design. SIAM Journal on Algebraic and Discrete Methods , 8(1):33--58, 1987. https://doi.org/10.1137/0608002 doi:10.1137/0608002
-
[14]
Linear layouts of graphs with priority queues
Emilio Di Giacomo , Walter Didimo, Henry F \" o rster, Torsten Ueckerdt, and Johannes Zink. Linear layouts of graphs with priority queues. In Pat Morin and Eunjin Oh, editors, Proc. 19th International Symposium on Algorithms and Data Structures (WADS 2025) , LIPIcs, pages 29:1--29:17. Schloss Dagstuhl - Leibniz-Zentrum f \" u r Informatik, 2025. https://d...
-
[15]
Emilio Di Giacomo , Walter Didimo, Giuseppe Liotta, and Stephen K. Wismath. Curve-constrained drawings of planar graphs. Comput. Geom. , 30(1):1--23, 2005. https://doi.org/10.1016/J.COMGEO.2004.04.002 doi:10.1016/J.COMGEO.2004.04.002
-
[16]
Emilio Di Giacomo , Walter Didimo, Giuseppe Liotta, and Stephen K. Wismath. Book embeddability of series-parallel digraphs. Algorithmica , 45(4):531--547, 2006. https://doi.org/10.1007/S00453-005-1185-7 doi:10.1007/S00453-005-1185-7
-
[17]
Dillencourt, David Eppstein, and Daniel S
Michael B. Dillencourt, David Eppstein, and Daniel S. Hirschberg. Geometric thickness of complete graphs. In Sue Whitesides, editor, Proc. 6th International Symposium on Graph Drawing (GD 1998) , volume 1547 of Lecture Notes in Computer Science , pages 101--110. Springer, 1998. https://doi.org/10.1007/3-540-37623-2\_8 doi:10.1007/3-540-37623-2\_8
-
[18]
Dillencourt, David Eppstein, and Daniel S
Michael B. Dillencourt, David Eppstein, and Daniel S. Hirschberg. Geometric thickness of complete graphs. In Graph Algorithms And Applications 2 , pages 39--51. World Scientific, 2004. https://doi.org/10.1142/9789812794741_0004 doi:10.1142/9789812794741_0004
-
[19]
Vida Dujmovic and David R. Wood. Graph treewidth and geometric thickness parameters. In Patrick Healy and Nikola S. Nikolov, editors, Proc. 13th International Symposium on Graph Drawing (GD 2005) , volume 3843 of Lecture Notes in Computer Science , pages 129--140. Springer, 2005. https://doi.org/10.1007/11618058\_13 doi:10.1007/11618058\_13
-
[20]
Vida Dujmovi \' c and David R. Wood. Graph treewidth and geometric thickness parameters. Disc. & Comp. Geom. , 37(4):641--670, 2007. https://doi.org/10.1007/s00454-007-1318-7 doi:10.1007/s00454-007-1318-7
-
[21]
Christian A. Duncan. On graph thickness, geometric thickness, and separator theorems. Comput. Geom. , 44(2):95--99, 2011. https://doi.org/10.1016/J.COMGEO.2010.09.005 doi:10.1016/J.COMGEO.2010.09.005
-
[22]
Sven Eggimann, Bernhard Truffer, and Max Maurer. To connect or not to connect? M odelling the optimal degree of centralisation for wastewater infrastructures. Water Research , 84:218--231, 2015. https://doi.org/10.1016/j.watres.2015.07.004 doi:10.1016/j.watres.2015.07.004
-
[23]
Separating geometric thickness from book thickness
David Eppstein. Separating geometric thickness from book thickness. arXiv preprint , 2001. https://arxiv.org/abs/math/0109195 arXiv:math/0109195
Pith/arXiv arXiv 2001
-
[24]
Separating thickness from geometric thickness
David Eppstein. Separating thickness from geometric thickness. In Proc. 10th International Symposium on Graph Drawing (GD 2002) , pages 150--162. Springer, 2002. https://doi.org/10.1007/3-540-36151-0_15 doi:10.1007/3-540-36151-0_15
-
[25]
Graphs that require many colors to achieve their chromatic sum
Paul Erd o s, Ewa Kubicka, and Allen Schwenk. Graphs that require many colors to achieve their chromatic sum. Congr. Numer. , 71, 1990
1990
-
[26]
orster. Graph Drawing Beyond the Beaten Tracks . PhD thesis, Universit\
Henry F\"orster. Graph Drawing Beyond the Beaten Tracks . PhD thesis, Universit\"at T\"ubingen, 2020. URL: http://hdl.handle.net/10900/108847
2020
-
[27]
Joseph L. Ganley and Lenwood Heath. The pagenumber of k -trees is O(k) . Disc. App. Math. , 109(3):215--221, 2001. https://doi.org/10.1016/S0166-218X(00)00178-5 doi:10.1016/S0166-218X(00)00178-5
-
[28]
A 27/26-approximation algorithm for the chromatic sum coloring of bipartite graphs
Krzysztof Giaro, Robert Janczewski, Marek Kubale, and Michal Malafiejski. A 27/26-approximation algorithm for the chromatic sum coloring of bipartite graphs. In Klaus Jansen, Stefano Leonardi, and Vijay V. Vazirani, editors, Proc. 5th International Workshop on Approximation Algorithms for Combinatorial Optimization (APPROX 2002) , volume 2462 of Lecture N...
-
[29]
Goldner and F
A. Goldner and F. Harary. Note on a smallest nonhamiltonian maximal planar graph. Bulletin of the Malaysian Math. Sci. Soc. , 1(6):41--42, 1975
1975
-
[30]
Algorithms for Incremental Planar Graph Drawing and Two-page Book Embeddings
Martin Gronemann. Algorithms for Incremental Planar Graph Drawing and Two-page Book Embeddings . PhD thesis, University of Cologne, 2015. URL: http://kups.ub.uni-koeln.de/id/eprint/6329
2015
-
[31]
Halld \' o rsson, Guy Kortsarz, and Hadas Shachnai
Magn \' u s M. Halld \' o rsson, Guy Kortsarz, and Hadas Shachnai. Minimizing average completion of dedicated tasks and interval graphs. In Michel X. Goemans, Klaus Jansen, Jos \' e D. P. Rolim, and Luca Trevisan, editors, Proc. 4th International Workshop on Approximation Algorithms for Combinatorial Optimization Problems (APPROX 2001) , volume 2129 of Le...
-
[32]
Embedding planar graphs in seven pages
Lenwood Heath. Embedding planar graphs in seven pages. In Proc. 25th Annual Symposium on Foundations of Computer Science (FOCS 1984) , pages 74--83. IEEE Comp. Soc., 1984. https://doi.org/10.1109/SFCS.1984.715903 doi:10.1109/SFCS.1984.715903
arXiv 1984
-
[33]
Lenwood S. Heath and Arnold L. Rosenberg. Laying out graphs using queues. SIAM J. Comput. , 21(5):927--958, 1992. https://doi.org/10.1137/0221055 doi:10.1137/0221055
-
[34]
Hopcroft and Robert Endre Tarjan
John E. Hopcroft and Robert Endre Tarjan. Efficient algorithms for graph manipulation [H] (algorithm 447). Commun. ACM , 16(6):372--378, 1973. https://doi.org/10.1145/362248.362272 doi:10.1145/362248.362272
arXiv 1973
-
[35]
Paul C. Kainen. Thickness and coarseness of graphs. In Abhandlungen aus dem Mathematischen Seminar der Universit \"a t Hamburg , volume 39, pages 88--95. Springer, 1973. https://doi.org/10.1007/bf02992822 doi:10.1007/bf02992822
-
[36]
Ewa M. Kubicka. Polynomial algorithm for finding chromatic sum for unicyclic and outerplanar graphs. Ars Comb. , 76, 2005
2005
-
[37]
Ewa M. Kubicka and Allen J. Schwenk. An introduction to chromatic sums. In Arthur M. Riehl, editor, Proc. 1989 ACM 17th Annual Computer Science Conference (CSC 1989) , pages 39--45. ACM , 1989. https://doi.org/10.1145/75427.75430 doi:10.1145/75427.75430
arXiv 1989
-
[38]
An annotated bibliography on the thickness, outerthickness, and arboricity of a graph
Erkki M \"a kinen and Timo Poranen. An annotated bibliography on the thickness, outerthickness, and arboricity of a graph. Missouri Journal of Mathematical Sciences , 24(1), 2012. https://doi.org/10.35834/mjms/1337950501 doi:10.35834/mjms/1337950501
arXiv 2012
-
[39]
A short proof of the NP -completeness of minimum sum interval coloring
D \' a niel Marx. A short proof of the NP -completeness of minimum sum interval coloring. Oper. Res. Lett. , 33(4):382--384, 2005. https://doi.org/10.1016/J.ORL.2004.07.006 doi:10.1016/J.ORL.2004.07.006
-
[40]
The thickness of graphs: A survey
Petra Mutzel, Thomas Odenthal, and Mark Scharbrodt. The thickness of graphs: A survey. Graphs Comb. , 14(1):59--73, 1998. https://doi.org/10.1007/PL00007219 doi:10.1007/PL00007219
-
[41]
T. Ollmann. On the book thicknesses of various graphs. In F. Hoffman, R.B. Levow, and R.S.D. Thomas, editors, Southeastern Conference on Combinatorics, Graph Theory and Computing , volume VIII of Cong. Num. , page 459, 1973
1973
-
[42]
Mixed linear layouts of planar graphs
Sergey Pupyrev. Mixed linear layouts of planar graphs. In Fabrizio Frati and Kwan - Liu Ma, editors, Proc. 25th International Symposium on Graph Drawing and Network Visualization (GD 2017) , volume 10692 of LNCS , pages 197--209. Springer, 2017. https://doi.org/10.1007/978-3-319-73915-1\_17 doi:10.1007/978-3-319-73915-1\_17
-
[43]
S. Rengarajan and C. E. Veni Madhavan. Stack and queue number of 2-trees. In Ding - Zhu Du and Ming Li, editors, Proc. 1st Annual International Conference on Computing and Combinatorics (COCOON 1995) , volume 959 of LNCS , pages 203--212. Springer, 1995. https://doi.org/10.1007/BFb0030834 doi:10.1007/BFb0030834
-
[44]
Stow, Yuan Xie, Taniya Siddiqua, and Gabriel H
Dylan C. Stow, Yuan Xie, Taniya Siddiqua, and Gabriel H. Loh. Cost-effective design of scalable high-performance systems using active and passive interposers. In Sri Parameswaran, editor, Proc. 2017 IEEE/ACM International Conference on Computer-Aided Design (ICCAD 2017) , pages 728--735. IEEE , 2017. https://doi.org/10.1109/ICCAD.2017.8203849 doi:10.1109/...
arXiv 2017
-
[45]
Kenneth J. Supowit. Finding a maximum planar subset of a set of nets in a channel. IEEE Trans. Comput. Aided Des. Integr. Circuits Syst. , 6(1):93--94, 1987. https://doi.org/10.1109/TCAD.1987.1270250 doi:10.1109/TCAD.1987.1270250
arXiv 1987
-
[46]
W.T. Tutte. The thickness of a graph. Indagationes Mathematicae (Proceedings) , 66:567--577, 1963. https://doi.org/10.1016/S1385-7258(63)50055-9 doi:10.1016/S1385-7258(63)50055-9
-
[47]
Arc diagrams: Visualizing structure in strings
Martin Wattenberg. Arc diagrams: Visualizing structure in strings. In Pak Chung Wong and Keith Andrews, editors, 2002 IEEE Symposium on Information Visualization (InfoVis 2002) , pages 110--116. IEEE Computer Society, 2002. https://doi.org/10.1109/INFVIS.2002.1173155 doi:10.1109/INFVIS.2002.1173155
Pith/arXiv arXiv 2002
-
[48]
Congruent graphs and the connectivity of graphs
Hassler Whitney. Congruent graphs and the connectivity of graphs. American Journal of Mathematics , 54(1):150--168, 1932. https://doi.org/10.2307/2371086 doi:10.2307/2371086
doi:10.2307/2371086 1932
-
[49]
The complexity of the H amiltonian circuit problem for maximal planar graphs
Avi Wigderson. The complexity of the H amiltonian circuit problem for maximal planar graphs. Technical Report 298, Dep. of Electrical Eng. and Comp. Science, Princeton University, 1982
1982
-
[50]
Four pages are necessary and sufficient for planar graphs (extended abstract)
Mihalis Yannakakis. Four pages are necessary and sufficient for planar graphs (extended abstract). In Juris Hartmanis, editor, Proc. 18th Annual ACM Symposium on Theory of Computing (STOC 1986) , pages 104--108. ACM , 1986. https://doi.org/10.1145/12130.12141 doi:10.1145/12130.12141
arXiv 1986
-
[51]
Embedding planar graphs in four pages
Mihalis Yannakakis. Embedding planar graphs in four pages. J. Comput. Syst. Sci. , 38(1):36--67, 1989. https://doi.org/10.1016/0022-0000(89)90032-9 doi:10.1016/0022-0000(89)90032-9
-
[52]
Planar graphs that need four pages
Mihalis Yannakakis. Planar graphs that need four pages. J. Comb. Theory, Ser. B , 145:241--263, 2020. https://doi.org/10.1016/j.jctb.2020.05.008 doi:10.1016/j.jctb.2020.05.008
This paper was first reviewed by grok-4.5 on July 31, 2026.
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