REVIEW 4 major objections 5 minor 26 references
Faster Algorithms for Deciding the Unbiased Maker-Breaker Triangle Game on General Graphs
T0 review · 4 major / 5 minor · reviewed 2026-08-01 · deepseek-v4-flash
Pith's one-line read The winner of the unbiased Maker-Breaker triangle game on any graph can be decided in O(n^7) time, down from O(n^16), by reading the game through its edge-triangle incidence graph.
desk verdict Strong algorithmic improvements for the Maker–Breaker triangle game, but the central theorem is an unproved translation from Kutz's thesis, so a referee needs to check that translation carefully. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The edge-triangle incidence graph ET(G): the bipartite graph with one vertex for each edge of G, one vertex for each triangle of G, and an edge between an edge-vertex and a triangle-vertex when that edge belongs to that triangle. It is the paper's central object: connected components of ET(G) after Breaker's moves are the arenas in which Maker's winning condition (WC) lives, and monotonicity of fastest winning strategies lets the algorithms examine only decreasing connected subgraphs. The other load-bearing piece is a structural characterization of Breaker's win on linear almost-3-uniform hypergraphs, translated into four graph conditions involving docks, shores, and ladders; the paper imple
What would settle it
Exhaustively compare the paper's conditions against brute-force game search on all small linear almost-3-uniform hypergraphs (or small graphs whose edge-triangle incidence graph is a cactus): the first instance whose conditions declare Breaker the winner while Maker has a winning strategy falsifies the base theorem and every algorithm built on it.
Extended reading notes
Core claim
On the paper's own terms, the central discovery is that the unbiased triangle game is governed by the edge-triangle incidence graph ET(G) rather than by the triangle hypergraph. Maker's winning condition (WC) is this: at some point after Breaker has claimed a set of edges, Maker has claimed two edge-vertices lying in the same connected component of ET(G) minus the closed neighborhood of Breaker's claimed edges. The paper shows that fastest winning strategies can be assumed monotone and that, until winning, every Maker move lies on a cycle in the remaining incidence graph. Building on a characterization of Breaker's win on linear almost-3-uniform hypergraphs, it converts these structural fact
Load-bearing premise
The load-bearing premise is that the characterization of Breaker's win on linear almost-3-uniform hypergraphs borrowed from earlier work is correct and complete; the paper cites it without proof, and if it has hidden hypotheses the general O(n^7) algorithm and both special-case algorithms collapse.
Editorial extensions
If this is right
- For any input graph, the winner can now be decided in O(n+m^3+m^2 t) ≤ O(n^7), a large improvement over the previous O(n^16) bound.
- If G contains K4 and ET(G) is connected, the winner can be decided in O(n+min{n^{ω+1},m^2}) time, where ω < 2.372 is the exponent of matrix multiplication; if a K4 witness is given, the bound improves to O(n+m^{1.5}).
- If ET(G) is a cactus graph, the winner is decided in O(n+m^{1.5}) = O(n^3), and Maker wins exactly when ET(G) contains a tadpole-fork.
- Deciding the triangle game is at least as hard as triangle detection: any graph can be transformed in linear time into a board graph that is Maker's win exactly when the original graph contains a triangle.
- Asymptotically, any graph with at least (1/4+ε)n^2 edges is Maker's win, and this is tight; minimal Maker-win graphs need at least 2n−1 edges, and this is tight for every n≥5.
Reading between the lines
- If the triangle-detection lower bound is tight, the general algorithm is still far from optimal; the K4 and cactus special cases suggest O(n^3) is a plausible target for all K4-free graphs.
- The monotonicity theorem is stated for the triangle game, but the proof mainly uses linearity of the induced hypergraph, so the same incidence-graph technique may yield faster algorithms for other Maker-Breaker games on fixed subgraphs with at most three edges.
- The linear-time reduction from triangle detection transfers fine-grained lower bounds: any subcubic algorithm for the game would imply a subcubic triangle-detection algorithm, making the game a natural candidate for fine-grained complexity classification.
- The extremal threshold (1/4+ε)n^2 for Maker's win is stated for raw edge counts; the paper itself notes the bipartite extremal example is artificial, and the open problem it poses — a threshold in triangle-to-edge ratio after removing reducible edges — is a testable route to a sharper bound.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper studies the unbiased Maker-Breaker triangle game on the edge set of a general graph G. It proposes viewing the game through the edge-triangle incidence graph ET(G) and claims three algorithmic results: (i) a general algorithm deciding the winner in O(n + m^3 + m^2 t) = O(n^7), improving the previous O(n^16) bound; (ii) an O(n + min{n^{ω+1}, m^2}) algorithm when G contains K4 and ET(G) is connected; and (iii) an O(n + m^{1.5}) algorithm when ET(G) is a cactus graph. It also gives a linear-time reduction from triangle detection to deciding the triangle game, and two extremal results: roughly n^2/4 edges force Maker's win (tight), and every minimal Maker win has at least 2n−1 edges (tight). The technical core is a structural characterization of Breaker's win in linear almost-3-uniform hypergraphs, translated from Kutz's thesis, and its application to triangle hypergraphs.
Significance. If the results are correct, the paper makes a substantial contribution: it reduces the polynomial-time bound for a natural Maker-Breaker game from O(n^16) to O(n^7), introduces the edge-triangle incidence graph as a useful algorithmic lens, provides a fine-grained lower bound via triangle detection, and gives tight extremal edge bounds with explicit extremal graphs. The claimed running times are concrete and the paper includes several novel structural characterizations (monotonicity of optimal winning strategies, the K4-based characterization, and the cactus/tadpole-fork characterization). However, the correctness of the central algorithms currently rests on two load-bearing gaps: an unproved translation of an external theorem and an inconsistent deletion convention that makes a key lemma false as stated. These issues must be resolved before the paper can be accepted.
major comments (4)
- [§2; Corollary 4.7] Under the stated definition of H+U in Section 2, H+U keeps hyperedges that survive as singletons. Corollary 4.7 is therefore false: deleting two degree-1 vertices from a 3-edge {v1,v2,v3} creates a 1-edge {v3}, which is an immediate Maker win. Concrete counterexample: the hypergraph H with edges {v1,v2,v3} and {v3,a} is Breaker-win, but H+{v1,v2} contains the 1-edge {v3} and is Maker-win. The proof's decomposition H = H1 ∪ H2 is invalid because H1 = H−{v1,v2} contains the shrunk edge {v3}, not the original hyperedge e. Since Corollary 4.7 is used in the proofs of Theorem 4.8 and Theorem 5.3, and indirectly in Corollary 4.10 and the main algorithms, this is load-bearing. The authors should either adopt the game-residual deletion (remove every hyperedge that intersects the deleted vertex set) and re-check all statements using H+U, or supply a correct argument under the stated convention.
- [§4.1, Theorem 4.4] Theorem 4.4, the central structural characterization, is not proved. The sentence 'The following theorem is obtained by interpreting Kutz' characterization of Breaker's win [20, Theorem 38] through the lens of the vertex-hyperedge incidence graph' is not a substitute for a proof. Theorem 4.5 verifies only that conditions (1)–(4) can be checked in linear time; it does not prove that those conditions are equivalent to Breaker's win. Corollary 4.10 applies this characterization to 2-connected components, and Theorem 4.12, Corollary 4.14, Theorem 4.19, and Theorem 4.22 all inherit the dependency. A missing or mistranslated hypothesis — for example on open docks or on ladder height when the optional path is absent — would invalidate the central O(n^7) claim. Please include a full proof of Theorem 4.4, or restate Kutz's original theorem exactly and prove the translation lemma by lemma.
- [§4.1, Theorem 4.12] The proof of Theorem 4.12 uses Lemma 4.11, quoted from [20, Lemma 24], to reduce the 3-uniform case to the almost-3-uniform case. Lemma 4.11 is not proved in the paper, and its hypotheses are not stated precisely enough to verify the enumeration over all pairs (v,w). Since this enumeration is the source of the |V|^2 factor in the claimed O(|V|^3 + |V|^2|E|) bound, the theorem is conditional as written. Please either prove Lemma 4.11 or give a complete statement, including all hypotheses, and a proof or exact reference.
- [§4.3, Theorem 4.22] The correctness proof of the cactus-graph algorithm is too terse. The text asserts that after pruning, a cycle attached to the rest of the graph by an edge-vertex 'also lies on a tadpole-fork', and that the reverse BFS order processes each cycle with at most one degree-3 vertex, but it does not rigorously prove that Step 9 detects a tadpole-fork exactly. Since Theorem 4.22 is one of the three main algorithmic results, please expand the correctness proof, ideally by stating and proving an explicit lemma that links the algorithm's local conditions to the existence of a tadpole-fork in ET(G).
minor comments (5)
- [Abstract] The abstract states the general running time as O(n + m^{3.5}), while the main text and Figure 1 give O(n + m^3 + m^2 t). Please make these consistent; the tighter bound is the one that should appear.
- [§3] Typo: 'contraindication' should be 'contradiction'.
- [§5.3] In the proof of Theorem 5.3, the equality n = |V(G')| = ℓ+2 depends on each newly added triangle sharing an edge with the previous union; please state this explicitly, since a triangle sharing only a vertex would not give the same count.
- [§4.2, Theorem 4.17] In the proof, condition (4) is introduced as a separate condition and used before condition (3) is proved, but it is not part of the theorem statement. Please either fold it into the statement or clarify the logical structure.
- [Several places] There are minor notational inconsistencies, e.g., the spelling 'bijection' and the use of 'B' for both a strategy and a set. A careful copyedit would improve readability.
Circularity Check
No significant circularity: the algorithms are deductive consequences of explicit lemmas, and the Kutz rank-3 characterization is used as an external black box, not a self-citation.
full rationale
The derivation chain is self-contained apart from explicitly cited external results. Lemma 3.1 proves an iff characterization of Breaker's win in terms of connected components of the edge-triangle incidence graph; Theorems 3.4, 3.7 and 3.8 give original proofs of monotonicity and cycle properties. Section 4 then applies Kutz's characterization: Theorem 4.4 is explicitly stated as 'obtained by interpreting Kutz' characterization of Breaker's win [20, Theorem 38]', with Kutz's thesis being an external source, not the authors' own work. Theorem 4.8 is proved in the paper by induction, and Corollary 4.10 and Theorem 4.12 are direct algorithmic consequences. The general O(n+m^3+m^2 t) bound is obtained by composing these results with Lemma 4.13, which gives an O(n+m^1.5) construction of the game hypergraph. The K4 and cactus special cases rest on Theorems 4.17 and 4.21, both of which are proved from Lemma 3.1 and other stated lemmas, not assumed. No parameter is fitted to data, and no 'prediction' is a renamed input. The only self-citation is [14] (Glazik–Srivastav), which appears in a survey sentence about the biased triangle game and is not used in any proof or as a load-bearing premise. The paper's reliance on the unproved faithful translation of Kutz's theorem is a correctness risk, but not circularity: the cited result is independent external work with stated assumptions, and the present paper does not derive the target result from itself.
Assumptions & free parameters
assumptions (4)
- domain assumption Kutz's characterization of Breaker's win on linear almost 3-uniform hypergraphs (Theorem 4.4) is correct and faithfully translated
- domain assumption Acyclic rank-3 hypergraphs are Breaker's win [13, Theorem 3.21]
- standard math Standard algorithmic results: ω<2.372, K4 detection in O(n^{ω+1}) [7], clique enumeration in O(m^2) [10], linear-time 2-connected components [17], triangle listing in O(m^{1.5}) [10]
- standard math Erdős–Stone theorem
Cite this review
Pith. "Pith review of Faster Algorithms for Deciding the Unbiased Maker-Breaker Triangle Game on General Graphs." pith.science (2026). https://pith.science/paper/YCQGSN7K
@misc{pith2026260718569,
author = {Pith},
title = {Pith review of: Faster Algorithms for Deciding the Unbiased Maker-Breaker Triangle Game on General Graphs},
year = {2026},
howpublished = {\url{https://pith.science/paper/YCQGSN7K}},
note = {Machine review of arXiv:2607.18569}
}
abstract
In this paper, we present new polynomial-time algorithms for determining the winner of the unbiased triangle game played on the edge set of general graphs. To that end, we propose to view the game through the edge-triangle incidence graph instead of the standard hypergraph model. We identify a necessary and sufficient winning condition for Maker in terms of the edge-triangle incidence graph and show that winning strategies achieving this condition as fast as possible play monotonically in the sense that they only consider monotonically decreasing connected subgraphs of the edge-triangle incidence graph. We give three different algorithms for different classes of graphs. For general graphs $G$, the outcome of the unbiased triangle game can be decided in time $\mathcal{O}(n+m^{3.5})=\mathcal{O}(n^7)$. This significantly improves on the $\mathcal{O}(n^{16})$ algorithm implied by the work of Galliot, Gravier and Sivignon (arXiv 2022). For graphs $G$ which contain $K_4$, the complete graph on four vertices, as a subgraph and whose edge-triangle incidence graph is connected, the winner can be decided in time $\mathcal{O}(n+\min\{n^{\omega+1},m^2\})=\mathcal{O}(n^{\omega+1})$, where $\omega<2.372$ is the exponent of matrix multiplication (Alman et. al., SODA 2025). For graphs $G$ whose edge-triangle incidence graph is a cactus graph, i.e. all its cycles are edge-disjoint, the winner can be decided in time $\mathcal{O}(n+m^{1.5})=\mathcal{O}(n^3)$. Such $G$ are $K_4$-free. The algorithms for the special cases are based on novel structural characterizations of Maker's win for each graph class. We also give a linear time reduction from triangle detection to deciding the unbiased triangle game.
Figures
Figures from the paper (9 more)
Reference graph
Works this paper leans on
-
[1]
More Asymmetry Yields Faster Matrix Multiplication
Josh Alman, Ran Duan, Virginia Vassilevska Williams, Yinzhan Xu, Zixuan Xu, and Renfei Zhou. More Asymmetry Yields Faster Matrix Multiplication. InProceedings of the 2025 Annual ACM-SIAM Symposium on Discrete Algorithms, pages 2005–2039. SIAM, 2025.doi:10.1137/1.9781611978322.63
-
[2]
OntheChvátal-ErdösTriangleGame.Electron.J.Comb.,18(1),2011
JózsefBaloghandWojciechSamotij. OntheChvátal-ErdösTriangleGame.Electron.J.Comb.,18(1),2011. doi:10.37236/559
-
[3]
O(n2.7799) Complexity for n*n Approximate Matrix Multiplication.Inf
Dario Bini, Milvio Capovani, Francesco Romani, and Grazia Lotti. O(n2.7799) Complexity for n*n Approximate Matrix Multiplication.Inf. Process. Lett., 8(5):234–235, 1979.doi:10.1016/0020-0190(79)90113-3
-
[4]
Maria Chudnovsky, Neil Robertson, Paul D. Seymour, and Robin Thomas. K4-free graphs with no odd holes.J. Comb. Theory B, 100(3):313–331, 2010.doi:10.1016/J.JCTB.2009.10.001. [5]Vašek Chvátal and Paul Erdös. Biased positional games. InAnn. Discrete Math., volume 2, pages 221–229. Elsevier, 1978
-
[6]
On the Asymptotic Complexity of Matrix multiplication (Extended Summary)
Don Coppersmith and Shmuel Winograd. On the Asymptotic Complexity of Matrix multiplication (Extended Summary). In22nd Annual Symposium on Foundations of Computer Science, pages 82–90. IEEE Computer Society, 1981.doi:10.1109/ SFCS.1981.27
1981
-
[7]
TowardsOptimalOutput-Sensitive Clique Listing or: Listing Cliques from Smaller Cliques
MinaDalirrooyfard,SuryaMathialagan,VirginiaVassilevskaWilliams,andYinzhanXu. TowardsOptimalOutput-Sensitive Clique Listing or: Listing Cliques from Smaller Cliques. InProceedings of the 56th Annual ACM Symposium on Theory of Computing, pages 923–934. ACM, 2024.doi:10.1145/3618260.3649663. [8]Reinhard Diestel.Graph Theory, 4th Edition, volume 173 ofGraduat...
arXiv 2024
-
[9]
Complexity of Maker-Breaker games on edge sets of graphs.Discret
Éric Duchêne, Valentin Gledel, Fionn Mc Inerney, Nicolas Nisse, Nacim Oijid, Aline Parreau, and Milos Stojakovic. Complexity of Maker-Breaker games on edge sets of graphs.Discret. Appl. Math., 361:502–522, 2025.doi:10.1016/J.DAM. 2024.11.012
doi:10.1016/j.dam 2025
-
[10]
Friedrich Eisenbrand and Fabrizio Grandoni. On the complexity of fixed parameter clique and dominating set.Theoretical Computer Science, 326(1):57–67, 2004.doi:10.1016/j.tcs.2004.05.009
Show all 26 references
-
[11]
Selfridge
Paul Erdös and John L. Selfridge. On a Combinatorial Game.J. Comb. Theory A, 14(3):298–301, 1973.doi:10.1016/ 0097-3165(73)90005-8
1973
- [12]
-
[13]
Maker-Breaker is solved in polynomial time on hypergraphs of rank 3.CoRR, abs/2209.12819, 2025.arXiv:2209.12819
Florian Galliot, Sylvain Gravier, and Isabelle Sivignon. Maker-Breaker is solved in polynomial time on hypergraphs of rank 3.CoRR, abs/2209.12819, 2025.arXiv:2209.12819
2025 arXiv
-
[14]
A new bound for the Maker-Breaker triangle game.Eur
Christian Glazik and Anand Srivastav. A new bound for the Maker-Breaker triangle game.Eur. J. Comb., 104:103536, 2022. doi:10.1016/J.EJC.2022.103536
2022
-
[15]
On the number of triangles in𝑘4-free graphs.CoRR, abs/2509.12100, 2025
Jialin He, Jie Ma, Yan Wang, and Chunlei Zu. On the number of triangles in𝑘4-free graphs.CoRR, abs/2509.12100, 2025. arXiv:2509.12100
2025
-
[16]
Birkhäuser Basel, 2014.doi:10.1007/978-3-0348-0825-5
Dan Hefetz, Michael Krivelevich, Miloš Stojaković, and Tibor Szabó.Positional Games, volume 44 ofOberwolfach Seminars. Birkhäuser Basel, 2014.doi:10.1007/978-3-0348-0825-5
2014 doi
-
[17]
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.doi:10.1145/362248.362272
1973
-
[18]
Finding a Minimum Circuit in a Graph.SIAM J
Alon Itai and Michael Rodeh. Finding a Minimum Circuit in a Graph.SIAM J. Comput., 7(4):413–423, 1978. doi: 10.1137/0207033
1978 doi
-
[19]
Solving Maker-Breaker Games on 5-uniform hypergraphs is PSPACE-complete.CoRR, abs/2502.20271, 2025.arXiv:2502.20271
Finn Orson Koepke. Solving Maker-Breaker Games on 5-uniform hypergraphs is PSPACE-complete.CoRR, abs/2502.20271, 2025.arXiv:2502.20271
2025 arXiv
-
[20]
Phd thesis, Freie Universität Berlin, 2004
Martin Kutz.The Angel Problem, Positional Games, and Digraph Roots. Phd thesis, Freie Universität Berlin, 2004. URL: https://refubium.fu-berlin.de/handle/fub188/9918
2004
-
[21]
Dimitrios Michail, Joris Kinable, Barak Naveh, and John V. Sichi. JGraphT - A Java Library for Graph Data Structures and Algorithms.ACM Trans. Math. Softw., 46(2):16:1–16:29, 2020.doi:10.1145/3381449
2020 doi
-
[22]
AthresholdfortheMaker-Breakercliquegame.RandomStruct.Algorithms,45(2):318–341, 2014.doi:10.1002/RSA.20489
TobiasMüllerandMilošStojaković. AthresholdfortheMaker-Breakercliquegame.RandomStruct.Algorithms,45(2):318–341, 2014.doi:10.1002/RSA.20489
2014 doi
-
[23]
Victor Y. Pan. Strassen’s Algorithm Is not Optimal: Trililnear Technique of Aggregating, Uniting and Canceling for Constructing Fast Algorithms for Matrix Operations. In19th Annual Symposium on Foundations of Computer Science, pages 166–176. IEEE Computer Society, 1978.doi:10....
1978 doi
-
[24]
6-UniformMaker-BreakerGameisPSPACE-Complete.Combinatorica,43(3):595–612, 2023.doi:10.1007/S00493-023-00026-7
MdLutfarRahmanandThomasWatson. 6-UniformMaker-BreakerGameisPSPACE-Complete.Combinatorica,43(3):595–612, 2023.doi:10.1007/S00493-023-00026-7
2023 doi
-
[25]
Some Properties of Disjoint Sums of Tensors Related to Matrix Multiplication.SIAM J
Francesco Romani. Some Properties of Disjoint Sums of Tensors Related to Matrix Multiplication.SIAM J. Comput., 11(2):263–267, 1982.doi:10.1137/0211020
1982 doi
-
[26]
Schaefer
Thomas J. Schaefer. On the Complexity of Some Two-Person Perfect-Information Games.J. Comput. Syst. Sci., 16(2):185–225, 1978.doi:10.1016/0022-0000(78)90045-4
1978 doi
-
[27]
Partial and Total Matrix Multiplication.SIAM J
Arnold Schönhage. Partial and Total Matrix Multiplication.SIAM J. Comput., 10(3):434–455, 1981.doi:10.1137/0210032. J. C. Brinkmann, A. Srivastav 31 [28]Volker Strassen. Gaussian Elimination is not Optimal.Numer. math, 13:354–356, 1969.doi:10.1007/BF02165411
1981 doi
-
[29]
Multiplying Matrices Faster Than Coppersmith-Winograd
Virginia Vassilevska Williams. Multiplying Matrices Faster Than Coppersmith-Winograd. InProceedings of the 44th Symposium on Theory of Computing Conference, pages 887–898. ACM, 2012.doi:10.1145/2213977.2214056
2012
Reviewed August 1, 2026 · model on record in the stance chip above.
Discussion (0). Continue with ORCID to comment.