(number-subtrees x)
returns the number of distinct subtrees of X, in the
sense of equal
Major Section: HONS-AND-MEMOIZATION
In the logic, number-subtrees
is defined as the length of
cons-subtrees
.
Under the hood, we first hons-copy
X to obtain a normed version, then
count the number of unique conses in X using an EQ hash table.