Huffman exhibits the greedy choice property.

**Proof:**

- Assume x and y have lowest frequencies.
- If x and y have lowest frequencies, then there exists an optimal code in which x and y are at the maximum depth (greedy choice).
- Greedy choice would put them where b and c are in T.
- Assume f(x) f(y) and f(b) f(c). We know f(x) f(b) and f(y) f(c).
- B(T) - B(T') =

- Thus, moving x to the bottom (similarly, y to the bottom) yields a better (optimal) solution.