Shuffle Mapping

In shuffle tracking, we do not normally attempt to follow cards through the shuffle without some preparation. We need a good idea of where segments of cards in the discard tray are likely to reside after the shuffle. For this, we need a shuffle map. Classically, this has been performed by hand with decks and magic markers. There are advantages to using software and the images here are from the CVShuffle mapper.

For demonstration purposes, let me start with a very simple six-deck, one-pass, riffle-and-restack (R&R) shuffle. (Note: This shuffle is now rare, although it does still exist.) After the plugging, break the pile in two, then take a grab from the top of each pile, riffle those two grabs (often more than once), put those cards down to form the base of the final pile, take another grab from the top of each of the two stacks created at the start, and continue until all of the cards are in the final pile.

In the image below, we see the cards prior to the shuffle on the left and after the shuffle on the right. We have colored the cards with eight electronic magic markers. Lines are drawn for each card giving the path from pre-shuffle to post-shuffle. In the post-shuffle stack, we see four segments, each a product of two of the original eight colors.

Now the above image assumes that the dealer riffles cards perfectly. That is, cards are perfectly interleaved when riffled together. It also assumes the dealer has segmented the original cards

 © 2009 Norman Wattenberger