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Old 01-26-2007, 11:00 PM   #7 (permalink)
Ganchrow
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Default 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 oi = decimal odds on the ith bet,
Let pi = win probability of the ith bet,
Let {k} = the set of all n single-bet Kelly stakes,
where ki = ith single-bet Kelly stake = MAX[(pi*oi-1)/(oi-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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