2021/02/02 by Qian, Bingchen, Xie, Chengfei, Ge, Gennian
#05C35 #Combinatorics (math.CO) #FOS: Mathematics
paper · doi:10.48550/arxiv.2102.01338
Erdős posed the problem of finding conditions on a graph G that imply the largest number of edges in a triangle-free subgraph is equal to the largest number of edges in a bipartite subgraph. We generalize this problem to general cases. Let δr be the least number so that any graph G on n vertices with minimum degree δrn has the property Pr-1(G)=Krf(G), where Pr-1(G) is the largest number of edges in an (r-1)-partite subgraph and Krf(G) is the largest number of edges in a Kr-free subgraph. We show that (3r-4)/(3r-1)