2 If two vertices z 1 and z 2 distinct from z are adjacent to [x 1 ], then no vertex is adjacent to [x 2 ] and N Q (z) = {x 0 ,
Chromatic Number, Independence Ratio, and Crossing Number, Ars Mathematica Contemporanea, vol.1, issue.1, pp.1-6, 2008. ,
Coloring graphs with given crossing patterns ,
Towards the Albertson Conjecture, Electronic Journal of Combinatorics, vol.17, p.73, 2010. ,
Graphs with Two Crossings Are 5-Choosable, SIAM Journal on Discrete Mathematics, vol.25, issue.4 ,
DOI : 10.1137/11082703X
5-Coloring Graphs with 4 Crossings, SIAM Journal on Discrete Mathematics, vol.25, issue.1, pp.401-422, 2011. ,
DOI : 10.1137/100784059
Sur leprobì eme des courbes gauches en topologie, Fund. Math, vol.15, pp.271-283, 1930. ,
Coloring graphs with crossings, Discrete Mathematics, vol.309, issue.9, pp.2948-2951, 2009. ,
DOI : 10.1016/j.disc.2008.07.040
Kuratowski's theorem, Journal of Graph Theory, vol.21, issue.3, pp.225-241, 1981. ,
DOI : 10.1002/jgt.3190050304
Every Planar Graph Is 5-Choosable, Journal of Combinatorial Theory, Series B, vol.62, issue.1, pp.180-181, 1994. ,
DOI : 10.1006/jctb.1994.1062