• Thumbnail for Hedetniemi's conjecture
    In graph theory, Hedetniemi's conjecture, formulated by Stephen T. Hedetniemi in 1966, concerns the connection between graph coloring and the tensor product...
    15 KB (1,853 words) - 15:10, 16 January 2025
  • Disproof of Hedetniemi's conjecture on the chromatic number of tensor products of graphs (Yaroslav Shitov, 2019) Kelmans–Seymour conjecture (Dawei He,...
    195 KB (20,026 words) - 13:12, 7 May 2025
  • powers conjecture Ganea conjecture Generalized Smith conjecture Hauptvermutung Hedetniemi's conjecture, counterexample announced 2019 Hirsch conjecture (disproved...
    35 KB (1,461 words) - 12:50, 10 May 2025
  • Thumbnail for Graph homomorphism
    also does. Identifying multiplicative graphs lies at the heart of Hedetniemi's conjecture. Graph homomorphisms also form a category, with graphs as objects...
    38 KB (4,860 words) - 20:28, 9 May 2025
  • Thumbnail for Tensor product of graphs
    ISBN 0-471-37039-8 Shitov, Yaroslav (May 2019), Counterexamples to Hedetniemi's conjecture, arXiv:1905.02167 Weichsel, Paul M. (1962), "The Kronecker product...
    8 KB (869 words) - 03:16, 15 December 2024
  • Thumbnail for Cartesian product of graphs
    {\displaystyle \chi (G\mathbin {\square } H)=\max\{\chi (G),\chi (H)\}.} The Hedetniemi conjecture states a related equality for the tensor product of graphs. The...
    11 KB (1,450 words) - 01:00, 26 March 2025
  • 5(1985), 247–256. The proof of El-Zahar and Norbert Sauer of the Hedetniemi's conjecture for 4-chromatic graphs. M. El-Zahar, N. W. Sauer: The chromatic...
    5 KB (412 words) - 04:15, 23 May 2025
  • Thumbnail for Four color theorem
    beyond", in Gera, Ralucca; Haynes, Teresa W.; Hedetniemi, Stephen T. (eds.), Graph Theory: Favorite Conjectures and Open Problems, II, Problem Books in Mathematics...
    49 KB (6,277 words) - 23:39, 14 May 2025
  • number, but with countably chromatic direct product. That is, Hedetniemi's conjecture fails for infinite graphs. In a paper with Paul Erdős he proved...
    17 KB (1,913 words) - 21:51, 3 February 2025
  • beyond", in Gera, Ralucca; Haynes, Teresa W.; Hedetniemi, Stephen T. (eds.), Graph Theory: Favorite Conjectures and Open Problems, II, Problem Books in Mathematics...
    11 KB (1,268 words) - 00:05, 18 April 2025
  • "Highly irregular", in Gera, Ralucca; Hedetniemi, Stephen; Larson, Craig (eds.), Graph Theory: Favorite Conjectures and Open Problems – 1, Problem Books...
    9 KB (467 words) - 00:32, 10 March 2025
  • years", in Gera, Ralucca; Haynes, Teresa W.; Hedetniemi, Stephen T. (eds.), Graph Theory: Favorite Conjectures and Open Problems – 2, Problem Books in Mathematics...
    4 KB (351 words) - 12:29, 27 April 2025
  • Thumbnail for Eternal dominating set
    by the publication of a paper on eternal domination by Goddard, Hedetniemi & Hedetniemi (2005), which also introduced a variation on the problem called...
    15 KB (1,820 words) - 01:07, 28 February 2025
  • years", in Gera, Ralucca; Haynes, Teresa W.; Hedetniemi, Stephen T. (eds.), Graph Theory: Favorite Conjectures and Open Problems – 2, Problem Books in Mathematics...
    35 KB (3,791 words) - 15:05, 25 March 2025
  • beyond", in Gera, Ralucca; Haynes, Teresa W.; Hedetniemi, Stephen T. (eds.), Graph Theory: Favorite Conjectures and Open Problems, II, Problem Books in Mathematics...
    15 KB (1,845 words) - 02:56, 19 August 2024
  • Thumbnail for Dominating set
    nonblocker, can be found by a fixed-parameter algorithm on any graph. Vizing's conjecture - relates the domination number of a cartesian product of graphs to the...
    31 KB (4,082 words) - 23:42, 29 April 2025
  • Thumbnail for Strong product of graphs
    beyond", in Gera, Ralucca; Haynes, Teresa W.; Hedetniemi, Stephen T. (eds.), Graph Theory: Favorite Conjectures and Open Problems, II, Problem Books in Mathematics...
    13 KB (1,316 words) - 03:24, 6 January 2024
  • Thumbnail for Salem–Spencer set
    and Spencer have a size that is nearly linear. This bound disproved a conjecture of Paul Erdős and Pál Turán that the size of such a set could be at most...
    22 KB (2,612 words) - 18:21, 10 October 2024
  • Thumbnail for Universal vertex
    vertex) has been considered with respect to the Aanderaa–Karp–Rosenberg conjecture on how many queries (subroutine calls) are needed to test whether a labeled...
    15 KB (1,942 words) - 00:39, 16 May 2025
  • Bayer-Fluckiger (born 1951), Hungarian-Swiss mathematician, proved Serre's conjecture on Galois cohomology of classical groups Jillian Beardwood (1934–2019)...
    196 KB (23,282 words) - 19:34, 18 May 2025