ylfink@water.UUCP (ylfink) (01/08/86)
DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF WATERLOO SEMINAR ACTIVITIES DATA STRUCTURING SEMINAR - Thursday, January 9, 1986. Dr. Jeffrey S. Vitter of Brown University will speak on ``Design and Analysis of Dynamic Huffman Coding''. TIME: 3:30 PM ROOM: MC 5158 ABSTRACT We introduce an efficient new algorithm for dynamic Huffman coding, called Algorithm V. It performs one- pass coding and transmission in real-time, and uses at most one more bit per letter than does the standard two-pass Huffman algorithm; this is optimum in the worst case among all one-pass schemes. We may analyze the dynamic Huffman algorithm due to Faller, Gallager, and Knuth. In each algorithm, both the sender and the receiver maintain equivalent dynamically varying Huff- man trees. The processing time required to encode and decode a letter whose node in the dynamic Huffman tree is currently on the lth level is O(l); hence, the pro- - - - cessing can be done in real time. Empirical tests show that Algorithm V performs quite well in practice, often better than the two-pass method. The proposed algo- rithm is well-suited for file compression and online encoding/decoding in data networks.