Assertion: tree's node | /r/AtLocation | a one-to-one correspondence
Facets:
Source sentences:
text: The nodes are thus in a one-to-one correspondence with finite (possibly empty) sequences of positive numbers, which are countable and can be placed in order first by sum of entries, and then by lexicographic order within a given sum (only finitely many sequences sum to a given value, so all entries are reached—