Blackjack Switch is a casino gambling game invented by Geoff Hall and patented in 2009.
After resolving any side bet, the dealer then consults each player in turn, initially asking them whether they wish to "switch" their top cards.
As in blackjack, a player hand which exceeds 21 is "bust"; its cards are removed and its backing wager acquired by the house.
While an often-quoted rule of thumb is to choose the option that forms or preserves the best single hand, this is unreliable; sometimes it is even correct to break up a natural by switching, for instance in the case AT + T[3-8] vs. dealer 7, 8 or 9.
Near-optimal schemes which can be learnt have been developed by several authors: Arnold Snyder presents a protocol for switching decisions based on four categories of hand, "winner", "push", "loser" and "chance"[4] which he claims reduces the house edge to 0.25% under his ruleset.
Cindy Liu presents a scheme based on assigning a point value to the dealt hands and those produced by switching.
Key: Blackjack Switch tables typically allow a side bet, called Super Match, which rewards pairs, three-of-a-kind, two-pairs or four-of-a-kind among the four initial cards comprising the players two hands.