The Labouchère system, also called the cancellation system or
split martingale, is a gambling strategy used in roulette. The
user of such a strategy decides before playing how much money
they want to win, and writes down a list of positive numbers
that sum to the predetermined amount. With each bet, the player
stakes an amount equal to the sum of the first and last numbers
on the list. If only one number remains, that number is the
amount of the stake.
If the bet is successful, the
two amounts are removed from the list. If the bet is
unsuccessful, the amount lost is appended to the end of the
list. This process continues until either the list is completely
crossed out, at which point the desired amount of money has been
won, or until the player runs out of money to wager. The system
is named for British politician and journalist Henry Labouchère,
who originally devised the strategy. ( )
The theory behind this Labouchère system is that, because the
player is crossing two numbers off of the list (win) for every
number added (loss) the player can complete the list, (crossing
out all numbers) thereby winning the desired amount even though
the player does not need to win as much as expected for this to
occur.
The Labouchère System is meant to be applied
to even money Roulette propositions such as Even/Odd, Red/Black
or 1–18/19–36. When any of these bets are made in the game of
Roulette, a spin resulting in a “0” or “00” results in a loss,
so even though the payout is even money, the odds are clearly
not 50/50. The Labouchère System attempts to offset these odds.
( )