Question 2 - Lempel Ziv codes/ written question
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A couple of students who came to my office hour
thought that the encoded message for Lempel-Ziv
(question 2-3) should correspond to the tree used
in parts 2-1 and 2-2.
IT DOESN'T.

The encoded message given in 2-3 stands on its own.
The beauty of LempelZiv codes is that the decoding process
can be done by looking at the encoded message (no additional
information or tree needs to be given).
As an example of how to decode looking at the encoded
message, refer to my lecture notes - Lecture 9 page 4
under heading "Decompressing". This can be done without 
looking back at the tree previously used for the encoding.

Lucia Moura