Imagine you compressed a file using your favorite compression algorithm, but you realize that there was a typo in the file. You then correct it, adding a single bit to the original file.

Compress it again and you get a much larger compressed file… for just a one-bit difference! Much compression algorithms do not have this strange behavior, but for LZ’78, one of the most famous of them, this surprising scenario might well happen. This is what we will overview in this post.

source: L