• Title of article

    The empire problem in even embeddings on closed surfaces with

  • Author/Authors

    Noguchi، نويسنده , , Kenta، نويسنده ,

  • Issue Information
    روزنامه با شماره پیاپی سال 2013
  • Pages
    8
  • From page
    1944
  • To page
    1951
  • Abstract
    Let M be a map on a closed surface F 2 and suppose that each country of the map has at most r disjoint connected regions. Such a map is called an r -pire map on F 2 . In 1890, Heawood proved that the countries of M can be properly colored with ⌊ ( 6 r + 1 + ( 6 r + 1 ) 2 − 24 ε ) / 2 ⌋ colors, where ε is the Euler characteristic of F 2 . Also, he conjectured that this is best possible except for the case ( ε , r ) = ( 2 , 1 ) , and now it is proved for all cases where ε ≥ 0 and some cases where ε < 0 . l a graph on F 2 an even embedding if it has no faces of boundary length odd. In this paper, we consider the r -pire maps whose underlying graphs are even embeddings on F 2 . In my recent paper, it was proved that such a map can be properly colored with ⌊ ( 4 r + 1 + ( 4 r + 1 ) 2 − 16 ε ) / 2 ⌋ colors. In this paper, we show the best possibility of this value for some cases where ε ≤ 0 .
  • Keywords
    Even embedding , Current graph , Empire problem
  • Journal title
    Discrete Mathematics
  • Serial Year
    2013
  • Journal title
    Discrete Mathematics
  • Record number

    1600416