Mathematics, Probability, Combinatorics.
deterministically calculate the function {(1, 2), (2, 3), (3, 1), (4, 0)} by assigning to every y in Y its number of occurrences. A function from {0, …, k} onto ℕ with a range summing to n-1 can be (bijectively) represented as a finite sequence with n+k-1 values, each one being a divider or a dot,