It might have been in Uston's book,million dollar blackjack.I believe if a 5 and no ace was played add a chip and if an ace and no 5 has been played decrease a chip.2 fives played add 2 chips,etc.something like that.Willi.
I also read in some book where it had math percentages for each card and the Ace was the most favorable card (% wise) for the player and the 5 was the most favorable (% wise) for the dealer. Anything out there to back this up?
It's something like .53 if a 5 is removed and the ace is good for the player because of the doubles and 3-2 blackjack.I would make sure you know the basic strategy of the game your playing first and then start with the other stuff.That ace-5 was for single deck most likely.Go to a Borders and look through all the books.I'd recomend professional blackjack by Wong.Willi.
Click on 'BJ Simulations' and then scroll down to the bottom of the page for Ace-Five info.
Ace-Five is the system I started out with. I can vouch for the fact that it is effective enough in single deck games to give you a modest advantage over the house, unless the rules and penetration are very poor. I didn't have much success with it in double deck games, though, which is why I switched to K-O, considering that single deck games are not available to me on a regular basis.
If you add the 4 as +1, A-4-5 is an unbalanced count that's only slightly harder than A-5, but it gets a better edge for single-deck, and it will get a small edge in double-deck (which A-5 has trouble with).
If you start the running count at 0, then the "key" count for raising in single-deck would be +2 with a max bet at +4. For double-deck, the key count would be +5 with a max bet at +8.
In 6-deck S17 DAS DOA, you can squeeze out slightly better than even if you use a large enough spread (about 12:1 or more), but the problem is a very large variance for a very tiny edge. (Of course, it's still better than playing a progression ;-)
I got interested in unbalanced systems from reading KO, too, and then from reading some of Brett Harris' posts on this board. Lately, I've been using KO in shoe games with the IRCs and keys adjusted downward by 4 and the pivot at 0. Most of the time, I just use the running count and the key, but for close situations like reaching the key early or late in the shoe, it's very easy to do a true count conversion to check it. I really think that Fuchs and Vancura should have defined KO this way, as an easy transition into TKO, beyond KO Prefered. Really, the only reason they defined it with the pivot at +4 was to make the pivot advantage close to that for Hi-Lo +4.
The pivot for an unbalanced system is just the net imbalance per deck times the number of decks. That (by definition) will be the only count that has a known advantage, at any point that it's reached in the deck. With this A-4-5 system, the +4 pivot will be somewhere around +1.5% advantage and up, depending on the starting disadvantage (which makes it pretty close to Hi-Lo +4).
The key count is determined by sims, and it really represents an average over the "typical" game rules and penetration. I got the numbers I posted using CVSim, which has a report showing the advantage at each running count number. The key is just the lowest running count that shows a definite advantage. (The KO keys seem to have about 0.25% advantage, on average of course.)