put down first main theorem is the Kraft McMillan inequality what it says is that for any uniquely decodable code c okay so this is somebody tells you I have a code it's uniquely decodable and if it's not uniquely decodable you can't really use it to do lossless compression so codes do need to be uniquely the code well unless we're not going to consider them for losses fresh when it comes up with a uniquely decodable code see what does that mean it means a mapping from symbols to bits bit strings corresponding to each symbol if it's