Wiki
Wiki

Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

Updated

Problem 583

../

claims/: The 9 claim pages of Problem 583, one per claimant's result; the problem's standing derives from them.


Statement. Every connected graph on nn vertices can be partitioned into at most ⌈n/2⌉\lceil n/2\rceil edge-disjoint paths.

Formulation. The site's wording, accessed 2026-09-18 (page last edited 1 April 2026). A partition into edge-disjoint paths is a path decomposition: every edge lies in exactly one of the paths. This is Gallai's conjecture; Erdős's 1971 statement, the site's source, asks whether "every connected graph of nn vertices is the union of [12(n+1)][\tfrac12(n+1)] edge disjoint paths" (item 11, p. 101), and [12(n+1)]=⌈n/2⌉[\tfrac12(n+1)]=\lceil n/2\rceil. The bound is sharp: in a graph with all degrees odd every vertex ends some path, so n/2n/2 paths are needed ([BoPe19], p. 1). Connectedness is needed: a disjoint union of triangles needs 2n/32n/3 paths, and for graphs that need not be connected the sharp bound is ⌊23n⌋\lfloor\tfrac23n\rfloor paths (Dean and Kouider, and Yan, as quoted on p. 2 of [BM22] and pp. 608--609 of [CFS14]; the site writes ⌈23n⌉\lceil\tfrac23n\rceil). Two neighbors are not the problem: the covering version, in which the paths may share edges, was proved by Fan in 2002 with ⌈n/2⌉\lceil n/2\rceil paths (the site's [Fa02]), and the ceiling-free strengthening of Bonamy and Perrett asks for ⌊n/2⌋\lfloor n/2\rfloor paths unless the graph is an odd semi-clique (Question 1.1).

Status. Falsifiable, the site's label for an open statement that a finite counterexample would refute; the standing here is open. A counterexample would be a connected graph on nn vertices whose every path decomposition has more than ⌈n/2⌉\lceil n/2\rceil paths, a property that finite enumeration decides for any given graph. No proof for all connected graphs and no counterexample is known. The conjecture is proved for connected graphs of maximum degree at most 55 (Bonamy and Perrett, Theorem 1.3; Discrete Math. 2019, refereed; claim page), for connected planar graphs (Blanché, Bonamy and Bonichon, Theorem 1.1; an extended abstract of 2021 and a 2022 preprint whose full proof has no journal version found; claim page) and for connected 22-degenerate graphs (Anto and Basavaraju, Theorem 1; DMTCS 2023, refereed; claim page), and, with ⌊n/2⌋\lfloor n/2\rfloor paths, for graphs in which every cycle contains a vertex of odd degree, that is, whose even-degree vertices induce a forest (Pyber, Theorem 0; J. Combin. Theory Ser. B 1996, refereed; claim page), and, with ⌊n/2⌋\lfloor n/2\rfloor paths, for graphs each block of whose even-degree subgraph is a triangle-free graph of maximum degree at most 33 (Fan, Corollary; J. Combin. Theory Ser. B 2005, refereed), and more generally for graphs whose even-degree subgraph is an α\alpha-graph (Fan, Main theorem; claim page), and, with ⌊n/2⌋+1\lfloor n/2\rfloor+1 paths, hence ⌈n/2⌉\lceil n/2\rceil when nn is odd, for graphs whose even-degree vertices induce a complete graph KmK_m with m≤15m\le15 (Chu, Fan and Zhou, Theorem 1.3; Discrete Math. 2026, refereed; claim page), and, second-hand through the cited papers' introductions and the site, for Lovász's class (at most one vertex of even degree; a proceedings paper; claim page), among others. An exhaustive computer check for n≤11n\le11 is reported in the site's discussion thread (claim page) and reproduced there with an independent decider (claim page); both are claimed partial results, not sources of status.

Source. erdosproblems.com/583, accessed 2026-09-18: the problem page (FALSIFIABLE, the label the site gives an open statement that a finite counterexample would refute; last edited 1 April 2026; source key [Er71, p. 101], with [Fa02], [Lo68], [Ch78], [Py96], [BoPe19], [BBB21], [AnBa23], [CFZ26] and [DeKo00] cited in the commentary, which also links the entry "EdgePartitionIntoPaths" of the graphs problem collection), its five-comment discussion thread (4 March to 17 September 2026) and its empty proof-claim tab. Cite as: T. F. Bloom, Erdős Problem #583, https://www.erdosproblems.com/583, accessed 2026-09-18.

References.

  • [Er71] Erdős, P., Some unsolved problems in graph theory and combinatorial analysis. Combinatorial Mathematics and its Applications (Proc. Conf., Oxford, 1969) (1971), 97--109; item 11, p. 101. Library home: erdos_1971_unsolved_problems_graph_theory_combinatorial_analysis (a scan); the passage is paged at item_11.
  • [BoPe19] Bonamy, Marthe and Perrett, Thomas J., Gallai's path decomposition conjecture for graphs of small maximum degree. Discrete Math. 342 (2019), no. 5, 1293--1299, doi:10.1016/j.disc.2019.01.005 (Crossref record read; not held); pages cited from arXiv:1609.06257v1 (20 September 2016, pagination 1--11). Conjecture 1.1 and the quoted Theorems 1.1--1.2, p. 1; Theorem 1.3 and Question 1.1, p. 2. Library home: bonamy_2019_gallai_s_path_decomposition_conjecture_graphs.
  • [BBB21] A. Blanché, M. Bonamy, and N. Bonichon, Gallai's path decomposition in planar graphs. arXiv:2110.08870 (v1 17 October 2021; v2 21 June 2022, 95 pp.). An extended abstract appeared in Extended Abstracts EuroComb 2021 (Trends in Mathematics), 758--764, doi:10.1007/978-3-030-83823-2_121 (not held). Theorems 1.1--1.2, p. 1. Library home: blanche_2021_gallai_s_path_decomposition_planar_graphs.
  • [AnBa23] Anto, Nevil and Basavaraju, Manu, Gallai's path decomposition for 2-degenerate graphs. Discrete Math. Theor. Comput. Sci. 25:1 (2023), Paper No. 16, 11 pp., doi:10.46298/dmtcs.10313 (accepted 4 May 2023, published 30 May 2023; arXiv:2211.07159v3 is the paper in the journal's typesetting). Conjecture 1, p. 1; Theorem 1 and Corollary 1, p. 2. Library home: anto_2023_gallai_s_path_decomposition_2_degenerate.
  • [CFZ26] Chu, Yanan and Fan, Genghua and Zhou, Chuixiang, Gallai's conjecture and the path number of odd semi-cliques. Discrete Math. 349 (2026), Paper No. 114725, 6 pp., doi:10.1016/j.disc.2025.114725 (received 18 December 2024, accepted 30 July 2025, available online 18 August 2025; the Crossref record read gives the issue date February 2026). Conjecture 1.1 and Theorem 1.2 (Lovász, quoted), p. 1; Theorems 1.3--1.5, the semi-clique definition, Conjecture 1.6 and Theorem 1.7, p. 2; the proof of Theorem 1.4, p. 6. Library home: chu_2026_gallai_s_conjecture_path_number_odd_semi_cliques; the results are paged at theorem_1_3 and theorem_1_7.
  • [Lo68] Lovász, L., On covering of graphs. Theory of Graphs (Proc. Colloq., Tihany, 1966) (1968), 231--236. Not held; quoted on p. 1 of [BoPe19], p. 1 of [AnBa23], p. 608 of [CFS14] (Theorem 1.1) and p. 2 of [BM22].
  • [Py96] Pyber, L., Covering the edges of a connected graph by paths. J. Combin. Theory Ser. B 66 (1996), 152--159, doi:10.1006/jctb.1996.0012. Theorem 0 (the forest case) and Lovász's theorem and corollary, p. 152; the odd semi-clique Example, Gallai's Conjecture, Theorems I and II (the covering bounds) and the Example on asymptotic versions, p. 153; the derivation of Theorem 0, p. 155. Library home: pyber_1996_covering_edges_connected_graph_paths; the results are paged at theorem_0 and theorem_i. Its forest theorem is also quoted as Theorem 1.1 of [BoPe19], in agreement with the printed statement.
  • [Fa02] Fan, Genghua, Subgraph coverings and edge switchings. J. Combin. Theory Ser. B 84 (2002), 54--83, doi:10.1006/jctb.2001.2063 (Crossref record). Not held; the covering version, ⌈n/2⌉\lceil n/2\rceil paths that may share edges, quoted from the site, p. 2 of [BM22] and p. 609 of [CFS14].
  • [Fa05] Fan, Genghua, Path decompositions and Gallai's conjecture. J. Combin. Theory Ser. B 93 (2005), 117--125, doi:10.1016/j.jctb.2004.09.008. Not cited by the site. The abstract, p. 117; Gallai's conjecture as stated, the survey paragraph with Lovász's ⌊n/2⌋\lfloor n/2\rfloor consequence and the disjoint-triangles example, and Definition 2.1 (α\alpha-operations), p. 118; Definition 2.2 and Propositions 2.3--2.6 (α\alpha-graphs), p. 119; the Main theorem, p. 124; the Corollary (the block condition), p. 125. Library home: fan_2005_path_decompositions_gallai_s_conjecture; the results are paged at corollary and main_theorem. Its Corollary is also quoted as Theorem 1.2 of [BoPe19], in agreement with the printed statement.
  • [Ch78] Chung, F. R. K., On partitions of graphs into trees. Discrete Math. 23 (1978), 23--30, doi:10.1016/0012-365X(78)90183-8 (Crossref record). Not held; quoted from the site.
  • [DeKo00] Dean, Nathaniel and Kouider, Mekkia, Gallai's conjecture for disconnected graphs. Discrete Math. 213 (2000), 43--54, doi:10.1016/S0012-365X(99)00167-3 (Crossref record). Not held; quoted from the site, p. 2 of [BM22] and p. 608 of [CFS14]. Yan's 1998 Arizona State University thesis, On path decompositions of graphs, is the independent source of the same bound per [BM22]; not held.
  • [BM22] Bucić, M. and Montgomery, R., Towards the Erdős-Gallai cycle decomposition conjecture. arXiv:2211.07689v2 (2023); Adv. Math. 437 (2024), 109434. Its p. 2 surveys the path problem. Library home: bucic_2022_towards_erdos_gallai_cycle_decomposition_conjecture.
  • [CFS14] Conlon, David and Fox, Jacob and Sudakov, Benny, Cycle packing. Random Structures Algorithms 45 (2014), 608--626. Theorem 1.1 (Lovász, quoted) and the paragraph on Gallai's problem, pp. 608--609. Library home: conlon_2014_cycle_packing.

Formalization. Statement only. The file ErdosProblems/583.lean of formal-conjectures (main as fetched, the link pinned to that revision) declares erdos_583 under category research open with proof sorry: for a finite connected simple graph GG there is a decomposition of GG into subgraphs that are paths (IsPathSubgraph: the subgraph traced by a walk with no repeated vertex) with at most ⌈∣V∣/2⌉\lceil|V|/2\rceil parts. The site's "Formalised statement?" indicator read "No" and "Yes" on 18 September 2026; the community database (teorth/erdosproblems) records the problem falsifiable (31 August 2025), the statement formalized since 7 September 2026 and no formal proof.

Current assessment

The question (site formulation of 2026-09-18). The statement above; FALSIFIABLE; last edited 1 April 2026. The commentary attributes the problem to Erdős and Gallai, says the covering version was proved by Fan [Fa02], and lists partial results for an arbitrary connected graph GG on nn vertices: Lovász [Lo68], a partition into at most ⌊n/2⌋\lfloor n/2\rfloor edge-disjoint paths and cycles, hence into at most n−1n-1 paths, and the conjecture itself when at most one vertex of GG has even degree; Chung [Ch78], ⌈n/2⌉\lceil n/2\rceil edge-disjoint trees; Pyber [Py96], a cover by n/2+O(n3/4)n/2+O(n^{3/4}) paths and the conjecture when the even-degree vertices induce a forest; Bonamy and Perrett [BoPe19], maximum degree ≤5\le5; Blanché, Bonamy and Bonichon [BBB21], planar graphs; Anto and Basavaraju [AnBa23], 22-degenerate graphs; Chu, Fan and Zhou [CFZ26], the conjecture when the even-degree vertices induce KmK_m with m≤15m\le15 and nn is odd; Dean and Kouider [DeKo00], ⌈23n⌉\lceil\tfrac23n\rceil edge-disjoint paths for all graphs, disconnected ones included, a bound the commentary calls sharp for that wider class, also obtained by Yan in a 1998 thesis; and Hajós's conjecture that a graph with all degrees even partitions into at most ⌊n/2⌋\lfloor n/2\rfloor edge-disjoint cycles. See also Problems 184 and 1017. The discussion thread has five comments, recorded below; the proof-claim tab is empty; the community database record says falsifiable.

The label. The site's falsifiable label is a body note on an open problem, not a claim: a counterexample would be a connected graph whose path number exceeds ⌈n/2⌉\lceil n/2\rceil, which enumerating its path decompositions would detect, and no counterexample or general proof is in the sources cited here; Problems 23, 64 and 97 carry the same label and the same note.

What is proved, class by class. Sources with library pages first, at claims-checked depth; no proof was read except the one-sentence derivation of Pyber's Theorem 0 from his Corollary 1.2 and Lovász's theorem (p. 155 of [Py96]) and the one-sentence derivation of Fan's Corollary from his Proposition 2.6 and Main theorem (p. 125 of [Fa05]) and the three-line derivation of Chu, Fan and Zhou's Theorem 1.3 from their Theorem 1.4 (p. 2 of [CFZ26]) with the one-paragraph proof of their Theorem 1.4 (p. 6) and the one-paragraph proofs of their Theorems 1.5 and 1.7 (p. 2), all of which were followed.

Class of connected graphsBound provedSourceStanding here
maximum degree at most 55⌈n/2⌉\lceil n/2\rceilBonamy--Perrett, Theorem 1.3Discrete Math. 2019, refereed; pages cited from the arXiv v1; claim page
planar⌈n/2⌉\lceil n/2\rceil; ⌊n/2⌋\lfloor n/2\rfloor except K3K_3, K5−K_5^-Blanché--Bonamy--Bonichon, Theorem 1.1, Theorem 1.2arXiv v2 (2022), 95 pp.; no journal version found; the EuroComb 2021 extended abstract (a proceedings volume) is not held and no evidence of its refereeing is recorded; claim page
22-degenerate⌊n/2⌋\lfloor n/2\rfloor except K3K_3Anto--Basavaraju, Theorem 1DMTCS 2023, refereed; claim page
at most one vertex of even degree⌈n/2⌉\lceil n/2\rceilLovász 1968quoted on p. 1 of [BoPe19] and [AnBa23], and with ⌊n/2⌋\lfloor n/2\rfloor on p. 118 of [Fa05] and, for graphs connected or not, as Theorem 1.2 on p. 1 of [CFZ26]; not held; claim page
even-degree vertices induce a forest (each cycle has a vertex of odd degree)⌊n/2⌋\lfloor n/2\rfloorPyber, Theorem 0J. Combin. Theory Ser. B 1996, refereed; stated for all graphs, connected or not; sharp for the odd semi-cliques (its Example, p. 153); also quoted as Theorem 1.1 of [BoPe19]; claim page
each block of the even-degree subgraph triangle-free with maximum degree ≤3\le3⌊n/2⌋\lfloor n/2\rfloorFan, CorollaryJ. Combin. Theory Ser. B 2005, refereed; stated for all graphs, connected or not; the triangle-free condition cannot be dropped (its example, p. 118); also quoted as Theorem 1.2 of [BoPe19]; not on the site; claim page
even-degree subgraph an α\alpha-graph (built from the empty graph by adding isolated vertices and vertices joined to independent α\alpha-pairs; contains the forests and the previous row's class)⌊n/2⌋\lfloor n/2\rfloorFan, Main theoremJ. Combin. Theory Ser. B 2005, refereed; stated for all graphs, connected or not; every α\alpha-graph is triangle-free; not on the site; claim page
even-degree vertices induce KmK_m, m≤15m\le15⌊n/2⌋+1\lfloor n/2\rfloor+1, which is ⌈n/2⌉\lceil n/2\rceil when nn is oddChu--Fan--Zhou, Theorem 1.3Discrete Math. 2026, refereed; stated for all graphs, connected or not; nn and mm have the same parity, so the odd case is mm odd; the site states the row for nn odd; claim page

For the semi-cliques themselves, the graphs on nn vertices with more than ⌊n/2⌋(n−1)\lfloor n/2\rfloor(n-1) edges, that is, KnK_n with nn odd minus at most (n−3)/2(n-3)/2 edges, which need ⌈n/2⌉\lceil n/2\rceil paths and are the exceptions of Question 1.1, [CFZ26] proves p(G)≤(4n+6)/7p(G)\le(4n+6)/7 (Chu--Fan--Zhou, Theorem 1.7, p. 2, from its Theorem 1.5 for graphs with a universal vertex); the conjecture asks for ⌈n/2⌉\lceil n/2\rceil on this class, and the paper's Conjecture 1.6, credited to Botler and Sambinelli, predicts that among connected graphs exactly the semi-cliques need more than ⌊n/2⌋\lfloor n/2\rfloor paths.

The introductions of [BoPe19], [BBB21] and [AnBa23] report further classes, none held here: graphs with all degrees 22 or 44 (Favaron and Kouider, 1988); 2k2k-regular graphs of large girth with two disjoint perfect matchings (Botler and Jiménez); maximal outerplanar graphs (Geng, Fang and Li, 2015); series-parallel graphs and planar 33-trees; treewidth at most 33, with ⌊n/2⌋\lfloor n/2\rfloor except K3K_3 and K5−eK_5-e (Botler, Sambinelli, Coelho and Lee, J. Graph Theory 93 (2020)); triangle-free planar graphs with ⌊n/2⌋\lfloor n/2\rfloor (Botler, Jiménez and Sambinelli, Discrete Math. 342 (2019)); maximum degree 66 with the degree-66 vertices independent, with ⌊n/2⌋\lfloor n/2\rfloor except K3K_3, K5K_5, K5−eK_5-e (Chu, Fan and Liu, Discrete Math. 344 (2021)); and a generalization of Fan's block condition (Botler and Sambinelli, J. Graph Theory 97 (2021)). The bibliographic identities are those printed in [AnBa23]'s reference list.

Bounds without a class restriction. Lovász's theorem gives n−1n-1 paths for every graph (quoted in [CFS14], Theorem 1.1, and [BM22], p. 2); Dean and Kouider, and independently Yan, give ⌊23n⌋\lfloor\tfrac23n\rfloor paths for every graph, connected or not, sharp for disjoint unions of triangles ([BM22], p. 2; [CFS14], pp. 608--609, "sharp for a disjoint union of triangles"). The site prints this bound with a ceiling; the two quoting papers print a floor, and the bound is an integer 2n/32n/3 in the sharp case, so the two forms differ only when 3∤n3\nmid n; the papers themselves are not held. The covering results (Pyber 1996, Fan 2002) and Chung's tree partition concern other pieces and do not bound the path number. Pyber's Theorem I (p. 153) covers every connected graph by n/2+O(n3/4)n/2+O(n^{3/4}) paths that may share edges, and his Theorem II by n/2+4e/nn/2+4e/n paths when there are ee edges; his Example on the same page shows that the analogous asymptotic statement for edge-disjoint paths, n/2+o(n)n/2+o(n), cannot be proved without the conjecture itself: a vertex joined by an edge to each of k≥2m+3k\ge2m+3 copies of an mm-vertex counterexample needs at least n/2+n/(2m+1)n/2+n/(2m+1) paths.

The thread (forum claims with provenance, not status). The site does not verify comments.

  • 14:27 on 4 March 2026, the account Alfaiz: a list of partial results (Pyber's forest case, Geng--Fang--Li on maximal outerplanar and 22-connected outerplanar graphs, Bonamy--Perrett, Blanché--Bonamy--Bonichon, and Chu, Fan and Liu on maximum degree 66); the site was updated.
  • 13:29 on 16 March 2026, the account Woett: Dean and Kouider's ⌊23n⌋\lfloor\tfrac23n\rfloor as the best unrestricted bound, Yan's thesis claimed for the same bound but not found online; the site was updated.
  • 14:13 on 16 March 2026, the account JakeMallen: a link to an uploaded copy of Yan's paper on a personal web page; that copy is not held.
  • 23:54 on 31 August 2026, the account sallerk: an exhaustive check at small nn, reporting that every connected graph with at most 1111 vertices satisfies the conjecture (11,716,57111{,}716{,}571 graphs at n=10n=10 and 1,006,700,5651{,}006{,}700{,}565 at n=11n=11), the enumeration split into shards whose counts are checked against the number of connected graphs (OEIS A001349); the comment argues the check is not vacuous, since at n=7n=7 to 1010 a growing share of the connected graphs (3636 of 853853 at n=7n=7; 6,666,7306{,}666{,}730 of 11,716,57111{,}716{,}571 at n=10n=10) is covered by none of the six listed partial results; it notes that the decision is over simple paths, not trails, that an independent decider agrees with the fast one for n≤7n\le7 only, and that n=12n=12 is not settled (35,633,63935{,}633{,}639 graphs left undecided by its heuristic); it links code and run records in a public repository and discloses that AI tools assisted the searches and computations. Recorded as a claimed partial result on its claim page; reproduced by the next comment's independent decider, not reviewed and given no credit by this corpus.
  • 17:15 on 17 September 2026, the account herong: an independent decider for the same check, pruning with a lower bound on the paths inside each component CC of the uncovered part, the largest of 11, ⌈oddC/2⌉\lceil\mathrm{odd}_C/2\rceil, ⌈ΔC/2⌉\lceil\Delta_C/2\rceil and ⌈mC/(nC−1)⌉\lceil m_C/(n_C-1)\rceil, summed over components; the ⌈Δ/2⌉\lceil\Delta/2\rceil term is the new one (a simple path uses at most two edges at a vertex). As a control, on all 261,080261{,}080 connected graphs of order 99 with the path budget cut to 44 and then to 33, the two implementations report the same sets of undecomposable graphs. Exhaustive runs at n=9n=9, 1010 and 1111 (261,080261{,}080, 11,716,57111{,}716{,}571 and 1,006,700,5651{,}006{,}700{,}565 graphs, the shard counts checked against OEIS A001349) find no counterexample and nothing undecided, reproducing the n≤11n\le11 result; the n=12n=12 sweep (164,059,830,476164{,}059{,}830{,}476 graphs) was reported as running, and no outcome was posted as of 2026-10-07. Code and logs are in a public repository (https://github.com/Darrenus/erdos583-gallai/tree/677a2da258d2bb7d1c1facad15e054521abe57bf, commits of 17 September 2026), and the comment discloses assistance from Claude (Anthropic). Recorded as a claimed partial result on its claim page; a thread computation, not reviewed.

Leads from the search (not status). Abstracts only, none held, none refereed as far as found: Gallai's conjecture for Cartesian products G□HG\Box H with GG unicyclic or bicyclic, and p(G□H)≤mn/2p(G\Box H)\le mn/2 when p(G)=no(G)/2p(G)=n_o(G)/2 (Chen and Wu, arXiv:2310.11189 and 2310.11704, October 2023); for the Levi graphs L1(m,k)L_1(m,k) (Sahu and Padinhatteeri, arXiv:2409.06298, v2 August 2025); for complete graphs minus stars and certain tadpoles (Wang and Zhang, arXiv:2210.16406, 2022); and a 2026 posted preprint titled "Gallai's Path Decomposition Conjecture for Graphs with Small Bowtie Boundaries" (SSRN, doi:10.2139/ssrn.7453518; title only, from a Crossref bibliographic query). None claims the general statement.

Search scope. The status rests on these routes; none found a proof for all connected graphs, a counterexample, or a proof claim.

  • The site: problem page, discussion thread and proof-claim tab; the community database record; formal-conjectures 583.lean at the pinned commit.
  • arXiv: the API records of 1609.06257 (v1 only), 2110.08870 (v2, no journal reference) and 2211.07159 (v3, with the DMTCS reference); the search abs:"Gallai" AND abs:"path decomposition" sorted by date (thirteen records, the newest of August 2025; the leads above, [AnBa23], [BoPe19], Botler--Sambinelli, Botler--Jiménez--Sambinelli, Botler et al. on treewidth 33, Jiménez--Wakabayashi, and two unrelated items). The API searches titles and abstracts only, so these zeros are weak.
  • Crossref: the records of doi:10.46298/dmtcs.10313 and doi:10.1016/j.disc.2025.114725, and bibliographic queries for [BoPe19] (its Discrete Math. record), [BBB21] (only the EuroComb extended abstract and a dissertation record), [Py96], [Fa02], [DeKo00] and [Ch78].
  • Semantic Scholar: the citation list of [BBB21], not obtained.
  • The primary sources: [BoPe19] pp. 1--2, [BBB21] pp. 1--2, [AnBa23] pp. 1--2 and its reference list, [Er71] pp. 101--102, [BM22] p. 2, [CFS14] pp. 608--609.

Not searched: MathSciNet, zbMATH, Google Scholar, X; the graphs problem collection page the site links (not obtained). Not held: [Lo68], [Fa02], [Ch78], [DeKo00], Yan's thesis, the journal text of [BoPe19], the EuroComb abstract of [BBB21], the further class papers listed above.

Remaining gaps. (1) Proof coverage is statements only: Theorem 1.3 of [BoPe19], Theorems 1.1--1.2 of [BBB21] and Theorem 1 of [AnBa23] are paged at claims checked; no proof was read. (2) The planar case rests on a preprint whose full proof (95 pages) has no journal version found; reopening condition: a journal record, or a refereed version, after which the preprint qualification is dropped. (3) The journal text of [BoPe19] was not compared with the 2016 preprint. (4) [Lo68] is not held, so one row of the table is second-hand; [Fa02] is not held, and nothing here cites it first-hand. [Py96], [Fa05] and [CFZ26] are cited from their printed text, so their rows are first-hand; their proofs beyond the derivations of Pyber's Theorem 0, Fan's Corollary and Chu, Fan and Zhou's Theorem 1.3, and the one-paragraph proofs of Chu, Fan and Zhou's Theorems 1.4 (p. 6), 1.5 and 1.7 (p. 2), were read for structure only. (5) The site's ⌈23n⌉\lceil\tfrac23n\rceil against the quoting papers' ⌊23n⌋\lfloor\tfrac23n\rfloor is recorded, not resolved with the site. (6) The thread's computation and its reproduction in the thread are unreviewed.

Known results

  • Bonamy--Perrett, Theorem 1.3 (2016; Discrete Math. 2019; claim page): maximum degree at most 55; Question 1.1: the ⌊n/2⌋\lfloor n/2\rfloor strengthening for connected graphs other than the odd semi-cliques.
  • Blanché--Bonamy--Bonichon, Theorem 1.1 and Theorem 1.2 (EuroComb 2021, arXiv 2021--2022; claim page): planar graphs, with ⌊n/2⌋\lfloor n/2\rfloor except K3K_3 and K5−K_5^-; a preprint.
  • Anto--Basavaraju, Theorem 1 (DMTCS 2023; claim page): connected 22-degenerate graphs, ⌊n/2⌋\lfloor n/2\rfloor except the triangle.
  • Erdős 1971, item 11: the question in Erdős's words, with Lovász's odd-valency case.
  • Pyber, Theorem 0 (J. Combin. Theory Ser. B 1996; claim page): ⌊n/2⌋\lfloor n/2\rfloor edge-disjoint paths when every cycle contains a vertex of odd degree, sharp for the odd semi-cliques; Theorem I: n/2+O(n3/4)n/2+O(n^{3/4}) covering paths for every connected graph, with the example that no asymptotic form of the conjecture is weaker than the conjecture.
  • Fan, Corollary (J. Combin. Theory Ser. B 2005; claim page): ⌊n/2⌋\lfloor n/2\rfloor edge-disjoint paths when each block of the even-degree subgraph is a triangle-free graph of maximum degree at most 33; Main theorem: the same when the even-degree subgraph is an α\alpha-graph, the class behind the Corollary and Pyber's forests.
  • Chu--Fan--Zhou, Theorem 1.3 (Discrete Math. 2026; claim page): ⌊n/2⌋+1\lfloor n/2\rfloor+1 edge-disjoint paths, hence ⌈n/2⌉\lceil n/2\rceil when nn is odd, when the even-degree vertices induce KmK_m with m≤15m\le15; Theorem 1.7: (4n+6)/7(4n+6)/7 paths for every semi-clique, a graph that needs at least ⌈n/2⌉\lceil n/2\rceil paths.
  • Lovász 1968 (quoted; claim page): the class in the table above; Dean--Kouider 2000 and Yan 1998 (quoted): ⌊23n⌋\lfloor\tfrac23n\rfloor paths for every graph.

Linked library material

These entries are derived from explicit links on library pages. They are navigation only and do not by themselves record mathematical progress.