antssuchasaveragedegreeandchromaticnumber,howprobabilistic methodsandtheregularitylemmahavepervadedextremalgraphtheory andRamseytheory,orhowtheentirelynewfieldofgraphminorsand tree-decompositionshasbroughtstandardmethodsofsurfacetopology tobearonlong-standingalgorithmicgraphproblems. Clearly,then,thetimehascomeforareappr...