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Join Date: 08-28-05
Location: Forest Hills, NY, Home of the Blitzkrieg Bop
Posts: 4,633
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Simultaneous-bet Kelly staking -- the general case (unconstrained and uncorrelated)
This is the more general case where we relax the constraint that all single-bet Kelly stakes need to be equal. For the sake of sanity, the weightings are defined recursively.
Given n uncorrelated binary bets, the "Kelly-optimal allocation" is the set of weightings for each of the 2n-1 n-or-fewer-team parlays (where a single bet is considered a 1-team parlay) that can be created from the n-single bets, which maximizes the expected logarithm of the bankroll.
Let oi = decimal odds on the ith bet,
Let pi = win probability of the ith bet,
Let ki = ith single-bet Kelly stake = MAX[(pi*oi-1)/(oi-1), 0],
Define κ(n,m,{B}) as the sum of the Kelly optimal weights for all m-team parlays made up of all bets included the set {B}, then
Code:
n
κ(n,m,{B}) = ∏ ki - ∑ κ(n,i,{B})
i Є {B} i=m+1
Example:
Code:
given:
k1 = 1%
k2 = 2%
k3 = 3%
k4 = 4%
k5 = 5%
κ(5,5,{1,2,3,4,5})
= (weighting of the 5-team parlay as % of bankroll)
= k1*k2*k3*k4*k5
= 1%*2%*3%*4%*5%
= 0.0000012%
κ(5,4,{1,2,3,4})
= (weighting of the 4-team parlay consisting of bets {1,2,3,4} as % of bankroll)
= k1*k2*k3*k4 - κ(5,5,{1,2,3,4})
= 1%*2%*3%*4% - κ(5,5,{1,2,3,4,5})
= 0.0000228%
κ(5,4,{1,2,3,5})
= (weighting of the 4-team parlay consisting of bets {1,2,3,5} as % of bankroll)
= k1*k2*k3*k5 - κ(5,5,{1,2,3,5})
= 1%*2%*3%*5% - κ(5,5,{1,2,3,4,5})
= 0.0000288%
κ(5,3,{1,2,3})
= (weighting of the 3-team parlay consisting of bets {1,2,3} as % of bankroll)
= k1*k2*k3 - κ(5,4,{1,2,3}) - κ(5,5,{1,2,3})
= 1%*2%*3% - κ(5,4,{1,2,3,4}) - κ(5,4,{1,2,3,5}) - κ(5,5,{1,2,3,4,5})
= 0.00054720%
etc.
And now a non-recursive statement of the same. Please forgive the abuse of notation.
Given n uncorrelated binary bets, define the "Kelly-optimal allocation" is the set of weightings for each of the 2n-1 n-or-fewer-team parlays (where a single bet is considered a 1-team parlay) that can be created from the n-single bets, which maximizes the expected logarithm of the bankroll.
Let o i = decimal odds on the i th bet,
Let p i = win probability of the i th bet,
Let { k} = the set of all n single-bet Kelly stakes,
where k i = i th single-bet Kelly stake = MAX[(p i*o i-1)/(o i-1), 0],
Define {P( k)} = the power set of { k}
Define {S({B},i)} = the set of all sets, {s} Є {P( k)} such that | {s}| = i, {S} ⊇ k{B},
where k{B} is the set of the single-bet Kelly weights associated with the elements of {B}
Define κ(n,m, {B}) as the Kelly optimal weight for the m-team parlay made up of all bets included in the set { B} (where |{ B}| = m).
Code:
n
κ(n,m,{B}) = ∑( (-1)i-m * ∏ kj)
i = m j Є {S({B},i)}
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