is_valid_tree_degree_sequence#

is_valid_tree_degree_sequence(degree_sequence)[source]#

Check if a degree sequence is valid for a tree.

Two conditions must be met for a degree sequence to be valid for a tree:

  1. The number of nodes must be one more than the number of edges.

  2. The degree sequence must be trivial or have only strictly positive node degrees.

Parameters:
degree_sequenceiterable

Iterable of node degrees.

Returns:
bool

Whether the degree sequence is valid for a tree.

str

Reason for invalidity, or dummy string if valid.