show there exist positive constants c1 and c2 such that for any n≥3, whenever T1 and T2 are two trees on the set of vertices X={1,2,...,n}, there exists a function f:X→{−1,+1} for which
x∈P∑f(x)<c1logn
for any path P that is a subgraph of T1 or T2 , but with an upper bound c2logn/loglogn the statement is no longer true. combinatoricsgraph theoryinequalities