Results 131 to 140 of about 10,088 (246)

DP-4-Colorability on Planar Graphs Excluding 7-Cycles Adjacent to 4- or 5-Cycles

open access: yesMathematics
In order to resolve Borodin’s Conjecture, DP-coloring was introduced in 2017 to extend the concept of list coloring. In previous works, it is proved that every planar graph without 7-cycles and butterflies is DP-4-colorable.
Fan Yang, Xiangwen Li, Ziwen Huang
doaj   +1 more source

Characterization and recognition of edge intersection graphs of 3-chromatic hypergraphs with multiplicity at most than two in the class of split graphs

open access: yesЖурнал Белорусского государственного университета: Математика, информатика, 2018
Let Lm(k) denote the class of edge intersection graphs of k-chromatic hypergraphs with multiplicity at most m. It is known that the problem of recognizing graphs from L1(k) is polynomially solvable if k = 2 and is NP-complete if k = 3.
Tatiana V. Lubasheva, Yury M. Metelsky
doaj  

Fermat Principle, Ramsey Theory and Metamaterials. [PDF]

open access: yesMaterials (Basel), 2023
Frenkel M, Shoval S, Bormashenko E.
europepmc   +1 more source

Forbidden subgraphs for graphs with planar line graphs

open access: bronze, 1972
D. L. Greenwell, Robert L. Hemminger
openalex   +1 more source

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