I know given a degree sequence of n vertices, we may find multiple nonisomorphic trees. So the question is how can we find such degree sequences of n vertices that only determine a unique unlabelled tree?
2026-05-15 07:05:49.1778828749
Find degree sequences of n vertices that determines a unique unlabelled tree
151 Views Asked by Bumbble Comm https://math.techqa.club/user/bumbble-comm/detail At
1
a degree sequence with just one vertex of degree above 1 is such a tree. same for a sequence with only two vertices of degree above 1, these will have to be neighbors in the tree and the rest are just leaves so only one way of setting them up. for three vertices of degree above 1 or more, if they all have the same degree then they can only form one unique path in the tree so that also works. however if at least one of them has a degree different than the others, you can create non-isomorphic variants by deciding whether to use that unique vertex to connect the two other vertices or use some other vertex for that. for four vertices of degree above 1 you can create non-isomorphic variants by deciding whether to connect them as a length-4 path or as a single vertex connecting the three others, the only exception to that rule is if all these vertices are of degree 2, which means they must form a path, this would work for arbitrary amount of vertices as long as non has degree above 2.
I think that sums them all.