@Article{GridWagner_Algorithmica,
AUTHOR = {Erik D. Demaine and MohammadTaghi Hajiaghayi and
Ken-ichi Kawarabayashi},
TITLE = {Algorithmic Graph Minor Theory: Improved Grid Minor Bounds
and {Wagner}'s Contraction},
JOURNAL = {Algorithmica},
journalurl = {https://www.springer.com/journal/453},
VOLUME = 54,
NUMBER = 2,
MONTH = {June},
YEAR = 2009,
PAGES = {142--180},
NOTE = {Special issue of selected papers from the 17th Annual
International Symposium on Algorithms and Computation, 2006.},
doi = {https://dx.doi.org/10.1007/s00453-007-9138-y},
dblp = {https://dblp.org/rec/journals/algorithmica/DemaineHK09},
comments = {This paper is also available from <A HREF="http://dx.doi.org/10.1007/s00453-007-9138-y">SpringerLink</A>.},
papers = {GridWagner_ISAAC2006},
copyright = {The paper is \copyright Springer-Verlag.},
}
First, we obtain the only known polynomial min-max relation for graphs that do not exclude any fixed minor, namely, map graphs and power graphs. Second, we obtain explicit (and improved) bounds on the min-max relation for an important class of graphs excluding a minor, namely, K3, k-minor-free graphs, using new techniques that do not rely on Graph Minor Theory. These two avenues lead to faster fixed-parameter algorithms for two families of graph problems, called minor-bidimensional and contraction-bidimensional parameters, which include feedback vertex set, vertex cover, minimum maximal matching, face cover, a series of vertex-removal parameters, dominating set, edge dominating set, R-dominating set, connected dominating set, connected edge dominating set, connected R-dominating set, and unweighted TSP tour. Third, we disprove a variation of Wagner's Conjecture for the case of graph contractions in general graphs, and in a sense characterize which graphs satisfy the variation. This result demonstrates the limitations of a general theory of algorithms for the family of contraction-closed problems (which includes, for example, the celebrated dominating-set problem). If this conjecture had been true, we would have had an extremely powerful tool for proving the existence of efficient algorithms for any contraction-closed problem, like we do for minor-closed problems via Graph Minor Theory.