Wednesday, November 14, 2007

Exam Correction

For the compression question part c) on the exam: "For a given input, X = x1, x2, x3, ...xn, there is exactly one Huffman tree which will produce a maximal compression ratio." The official answer we graded by was "sometimes" The one instance where there is exactly one tree for the maximum compression ratio is for an empty file (only 1 such tree exists). Since we wrote "x1, x2, x3, ...xn", it is not clear that the length of the file could be 0. So if you wrote "sometimes" or "never" you should receive full credit. If you need a score correction for THIS part of the question, please contact YOUR TA for a score change.