Generalized Ramsey numbers for paths in 2-chromatic graphs.
We prove that for every number , the -iterated -path graph of is isomorphic to if and only if is a collection of cycles, each of length at least 4. Hence, is isomorphic to if and only if is a collection of cycles, each of length at least 4. Moreover, for we reduce the problem of characterizing graphs such that to graphs without cycles of length exceeding .
For any and any , a graph is introduced. Vertices of are -tuples over and two -tuples are adjacent if they are in a certain relation. These graphs are graphs of a particular variant of the Tower of Hanoi problem. Namely, the graphs are isomorphic to the graphs of the Tower of Hanoi problem. It is proved that there are at most two shortest paths between any two vertices of . Together with a formula for the distance, this result is used to compute the distance between two vertices in...