Oh, I wondered if you were going to ask that. Here's what I remember. 1) Dictionary size: For maximum compression, the dictionary needs to be as large as possible, and be kept in RAM memory for speed access. This tends to lead to memory hogging which just gets worse with time. 2) For successful communication, both parties must be using the same compression system and dictionary. If not, what comes out at the receiver end is gibberish. This means they must both be updating their dictionaries in identical fashion and may require one to send a large dictionary to the other first. 3) Dictionaries tend to be specific to the type of material transmitted between two people (for maximum efficiency). Therefore if they have a conversation about physics, it builds a physics term dictionary. If they start a new conversation about enrolling their children in school, the physics dictionary is not much use, and efficiency drops off until enough terms are learned. Really this would be better with a dictionary for each subject. That's all I can think of right now. Nigel wrote: > > > > > When sending information, these sequences are identified first and > short > > codes are sent instead. In fact, the long repeating sequences never > need > > to be sent again. One code identifies which information to decode at > the > > far end. The longer these sequences, the better the improvement in > speed > > because the time that would have been spent sending them is saved. > > > > If that's not so easy to follow, just think of it as a clever > > compression system. It does indeed get better with time, but it has > some > > disadvantages too. > > > > What are the disadvantages? > Nigel -- Regards, John Durham <mailto:modec@xxxxxxxxxxxxxx > ICQ number 112663246 Fax/Phone 64 4 5286786 Award winning web site at http://modecideas.com?sig Order my latest e-book at http://modecideas.com/dmaxhits.htm?sig PC-HELPERS list subscribe/unsub at http://pchelpers.5er.com?sig Referralware http://www.referralware.com/home.jsp/101728230 P.S. In case you're interested in such things, here is the most effective tool for getting masses of people to visit your website I have found: http://www.startblaze.com/cgi-bin/r_sb.cgi?id=11590&c=sbsigman2 Good advice is like good paint- it only works if applied.