5890b74225
* new standard resolution; contract.totalBets; MKT resolution * recalculate script * Fix one bug and change script name Co-authored-by: jahooma <jahooma@gmail.com>
117 lines
3.4 KiB
TypeScript
117 lines
3.4 KiB
TypeScript
import { Bet } from './firebase/bets'
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import { Contract } from './firebase/contracts'
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const fees = 0.02
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export function getProbability(pool: { YES: number; NO: number }) {
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const [yesPool, noPool] = [pool.YES, pool.NO]
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const numerator = Math.pow(yesPool, 2)
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const denominator = Math.pow(yesPool, 2) + Math.pow(noPool, 2)
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return numerator / denominator
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}
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export function getProbabilityAfterBet(
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pool: { YES: number; NO: number },
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outcome: 'YES' | 'NO',
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bet: number
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) {
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const [YES, NO] = [
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pool.YES + (outcome === 'YES' ? bet : 0),
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pool.NO + (outcome === 'NO' ? bet : 0),
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]
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return getProbability({ YES, NO })
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}
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export function calculateShares(
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pool: { YES: number; NO: number },
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bet: number,
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betChoice: 'YES' | 'NO'
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) {
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const [yesPool, noPool] = [pool.YES, pool.NO]
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return betChoice === 'YES'
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? bet + (bet * noPool ** 2) / (yesPool ** 2 + bet * yesPool)
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: bet + (bet * yesPool ** 2) / (noPool ** 2 + bet * noPool)
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}
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export function calculatePayout(
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contract: Contract,
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bet: Bet,
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outcome: 'YES' | 'NO' | 'CANCEL'
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) {
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const { amount, outcome: betOutcome, shares } = bet
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if (outcome === 'CANCEL') return amount
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if (betOutcome !== outcome) return 0
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const { totalShares, totalBets } = contract
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if (totalShares[outcome] === 0) return 0
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const startPool = contract.startPool.YES + contract.startPool.NO
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const truePool = contract.pool.YES + contract.pool.NO - startPool
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if (totalBets[outcome] >= truePool)
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return (amount / totalBets[outcome]) * truePool
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const total = totalShares[outcome] - totalBets[outcome]
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const winningsPool = truePool - totalBets[outcome]
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return (1 - fees) * (amount + ((shares - amount) / total) * winningsPool)
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}
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export function resolvedPayout(contract: Contract, bet: Bet) {
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if (contract.resolution)
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return calculatePayout(contract, bet, contract.resolution)
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throw new Error('Contract was not resolved')
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}
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export function currentValue(contract: Contract, bet: Bet) {
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const prob = getProbability(contract.pool)
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const yesPayout = calculatePayout(contract, bet, 'YES')
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const noPayout = calculatePayout(contract, bet, 'NO')
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return prob * yesPayout + (1 - prob) * noPayout
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}
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export function calculateSaleAmount(contract: Contract, bet: Bet) {
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const { shares, outcome } = bet
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const { YES: yesPool, NO: noPool } = contract.pool
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const { YES: yesStart, NO: noStart } = contract.startPool
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const { YES: yesShares, NO: noShares } = contract.totalShares
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const [y, n, s] = [yesPool, noPool, shares]
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const shareValue =
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outcome === 'YES'
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? // https://www.wolframalpha.com/input/?i=b+%2B+%28b+n%5E2%29%2F%28y+%28-b+%2B+y%29%29+%3D+c+solve+b
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(n ** 2 +
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s * y +
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y ** 2 -
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Math.sqrt(
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n ** 4 + (s - y) ** 2 * y ** 2 + 2 * n ** 2 * y * (s + y)
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)) /
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(2 * y)
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: (y ** 2 +
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s * n +
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n ** 2 -
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Math.sqrt(
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y ** 4 + (s - n) ** 2 * n ** 2 + 2 * y ** 2 * n * (s + n)
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)) /
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(2 * n)
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const startPool = yesStart + noStart
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const pool = yesPool + noPool - startPool
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const probBefore = yesPool ** 2 / (yesPool ** 2 + noPool ** 2)
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const f = pool / (probBefore * yesShares + (1 - probBefore) * noShares)
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const myPool = outcome === 'YES' ? yesPool - yesStart : noPool - noStart
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const adjShareValue = Math.min(Math.min(1, f) * shareValue, myPool)
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const saleAmount = (1 - fees) * adjShareValue
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return saleAmount
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}
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