liquidity provision tracking

common/antes.ts

@@ -1,23 +1,13 @@
 import { Bet } from './bet'
 import { getDpmProbability } from './calculate-dpm'
-import { getCpmmProbability } from './calculate-cpmm'
+import { getCpmmLiquidity, getCpmmProbability } from './calculate-cpmm'
 import { Binary, CPMM, DPM, FreeResponse, FullContract } from './contract'
 import { User } from './user'
+import { LiquidityProvision } from './liquidity-provision'
 
 export const PHANTOM_ANTE = 0.001
 export const MINIMUM_ANTE = 10
 
-export const calcStartCpmmPool = (initialProbInt: number, ante: number) => {
-  const p = initialProbInt / 100.0
-
-  const [poolYes, poolNo] =
-    p >= 0.5 ? [ante * (1 / p - 1), ante] : [ante, ante * (1 / (1 - p) - 1)]
-
-  const k = poolYes * poolNo
-
-  return { poolYes, poolNo, k }
-}
-
 export function getCpmmAnteBet(
   creator: User,
   contract: FullContract<CPMM, Binary>,
@@ -45,20 +35,27 @@ export function getCpmmAnteBet(
   return bet
 }
 
-export const calcStartPool = (initialProbInt: number, ante = 0) => {
-  const p = initialProbInt / 100.0
-  const totalAnte = PHANTOM_ANTE + ante
+export function getCpmmInitialLiquidity(
+  creator: User,
+  contract: FullContract<CPMM, Binary>,
+  anteId: string,
+  amount: number
+) {
+  const { createdTime, pool } = contract
+  const liquidity = getCpmmLiquidity(pool)
 
-  const sharesYes = Math.sqrt(p * totalAnte ** 2)
-  const sharesNo = Math.sqrt(totalAnte ** 2 - sharesYes ** 2)
+  const lp: LiquidityProvision = {
+    id: anteId,
+    userId: creator.id,
+    contractId: contract.id,
+    createdTime,
+    isAnte: true,
 
-  const poolYes = p * ante
-  const poolNo = (1 - p) * ante
+    amount: amount,
+    liquidity,
+  }
 
-  const phantomYes = Math.sqrt(p) * PHANTOM_ANTE
-  const phantomNo = Math.sqrt(1 - p) * PHANTOM_ANTE
-
-  return { sharesYes, sharesNo, poolYes, poolNo, phantomYes, phantomNo }
+  return lp
 }
 
 export function getAnteBets(

common/bet.ts

@@ -19,6 +19,7 @@ export type Bet = {
 
   isSold?: boolean // true if this BUY bet has been sold
   isAnte?: boolean
+  isLiquidityProvision?: boolean
 
   createdTime: number
 }

common/calculate-cpmm.ts

@@ -24,11 +24,11 @@ export function calculateCpmmShares(
   pool: {
     [outcome: string]: number
   },
-  k: number,
   bet: number,
   betChoice: string
 ) {
   const { YES: y, NO: n } = pool
+  const k = y * n
   const numerator = bet ** 2 + bet * (y + n) - k + y * n
   const denominator = betChoice === 'YES' ? bet + n : bet + y
   const shares = numerator / denominator
@@ -40,9 +40,9 @@ export function calculateCpmmPurchase(
   bet: number,
   outcome: string
 ) {
-  const { pool, k } = contract
+  const { pool } = contract
 
-  const shares = calculateCpmmShares(pool, k, bet, outcome)
+  const shares = calculateCpmmShares(pool, bet, outcome)
   const { YES: y, NO: n } = pool
 
   const [newY, newN] =
@@ -60,11 +60,11 @@ export function calculateCpmmShareValue(
   shares: number,
   outcome: string
 ) {
-  const { pool, k } = contract
+  const { pool } = contract
   const { YES: y, NO: n } = pool
 
   const poolChange = outcome === 'YES' ? shares + y - n : shares + n - y
-
+  const k = y * n
   const shareValue = 0.5 * (shares + y + n - Math.sqrt(4 * k + poolChange ** 2))
   return shareValue
 }
@@ -101,3 +101,61 @@ export function getCpmmProbabilityAfterSale(
   const { newPool } = calculateCpmmSale(contract, bet)
   return getCpmmProbability(newPool)
 }
+
+export const calcCpmmInitialPool = (initialProbInt: number, ante: number) => {
+  const p = initialProbInt / 100.0
+
+  const [poolYes, poolNo] =
+    p >= 0.5 ? [ante * (1 / p - 1), ante] : [ante, ante * (1 / (1 - p) - 1)]
+
+  return { poolYes, poolNo }
+}
+
+export function getCpmmLiquidity(pool: { [outcome: string]: number }) {
+  // For binary contracts only.
+  const { YES, NO } = pool
+  return Math.sqrt(YES * NO)
+}
+
+export function addCpmmLiquidity(
+  contract: FullContract<CPMM, Binary>,
+  amount: number
+) {
+  const { YES, NO } = contract.pool
+  const p = getCpmmProbability({ YES, NO })
+
+  const [newYes, newNo] =
+    p >= 0.5
+      ? [amount * (1 / p - 1), amount]
+      : [amount, amount * (1 / (1 - p) - 1)]
+
+  const betAmount = Math.abs(newYes - newNo)
+  const betOutcome = p >= 0.5 ? 'YES' : 'NO'
+
+  const poolLiquidity = getCpmmLiquidity({ YES, NO })
+  const newPool = { YES: YES + newYes, NO: NO + newNo }
+  const resultingLiquidity = getCpmmLiquidity(newPool)
+  const liquidity = resultingLiquidity - poolLiquidity
+
+  return { newPool, liquidity, betAmount, betOutcome }
+}
+
+export function removeCpmmLiquidity(
+  contract: FullContract<CPMM, Binary>,
+  liquidity: number
+) {
+  const { YES, NO } = contract.pool
+  const poolLiquidity = getCpmmLiquidity({ YES, NO })
+  const p = getCpmmProbability({ YES, NO })
+
+  const f = liquidity / poolLiquidity
+  const [payoutYes, payoutNo] = [f * YES, f * NO]
+
+  const betAmount = Math.abs(payoutYes - payoutNo)
+  const betOutcome = p >= 0.5 ? 'NO' : 'YES' // opposite side as adding liquidity
+  const payout = Math.min(payoutYes, payoutNo)
+
+  const newPool = { YES: YES - payoutYes, NO: NO - payoutNo }
+
+  return { newPool, payout, betAmount, betOutcome }
+}

common/calculate-dpm.ts

@@ -271,3 +271,23 @@ export const deductDpmFees = (betAmount: number, winnings: number) => {
     ? betAmount + (1 - FEES) * (winnings - betAmount)
     : winnings
 }
+
+export const calcDpmInitialPool = (
+  initialProbInt: number,
+  ante: number,
+  phantomAnte: number
+) => {
+  const p = initialProbInt / 100.0
+  const totalAnte = phantomAnte + ante
+
+  const sharesYes = Math.sqrt(p * totalAnte ** 2)
+  const sharesNo = Math.sqrt(totalAnte ** 2 - sharesYes ** 2)
+
+  const poolYes = p * ante
+  const poolNo = (1 - p) * ante
+
+  const phantomYes = Math.sqrt(p) * phantomAnte
+  const phantomNo = Math.sqrt(1 - p) * phantomAnte
+
+  return { sharesYes, sharesNo, poolYes, poolNo, phantomYes, phantomNo }
+}

common/calculate.ts

@@ -28,11 +28,12 @@ export function getProbability(contract: FullContract<DPM | CPMM, Binary>) {
     : getDpmProbability(contract.totalShares)
 }
 
+// TODO: Deprecate this function
 export function getInitialProbability(
   contract: FullContract<DPM | CPMM, Binary>
 ) {
   return contract.mechanism === 'cpmm-1'
-    ? getCpmmProbability(contract.liquidity[contract.creatorId])
+    ? getCpmmProbability(contract.pool)
     : getDpmProbability(contract.phantomShares ?? contract.totalShares)
 }
 
@@ -62,7 +63,7 @@ export function calculateShares(
   betChoice: string
 ) {
   return contract.mechanism === 'cpmm-1'
-    ? calculateCpmmShares(contract.pool, contract.k, bet, betChoice)
+    ? calculateCpmmShares(contract.pool, bet, betChoice)
     : calculateDpmShares(contract.totalShares, bet, betChoice)
 }
 

common/contract.ts

@@ -46,10 +46,7 @@ export type DPM = {
 
 export type CPMM = {
   mechanism: 'cpmm-1'
-
   pool: { [outcome: string]: number }
-  k: number // liquidity constant
-  liquidity: { [userId: string]: { [outcome: string]: number } } // track liquidity providers
 }
 
 export type FixedPayouts = CPMM

common/liquidity-provision.ts

@@ -0,0 +1,11 @@
+export type LiquidityProvision = {
+  id: string
+  userId: string
+  contractId: string
+
+  createdTime: number
+  isAnte?: boolean
+
+  amount: number // M$ quantity
+  liquidity: number // sqrt(k)
+}

common/new-contract.ts

@@ -1,4 +1,4 @@
-import { calcStartPool, calcStartCpmmPool } from './antes'
+import { PHANTOM_ANTE } from './antes'
 import {
   Binary,
   Contract,
@@ -10,6 +10,8 @@ import {
 import { User } from './user'
 import { parseTags } from './util/parse'
 import { removeUndefinedProps } from './util/object'
+import { calcCpmmInitialPool } from './calculate-cpmm'
+import { calcDpmInitialPool } from './calculate-dpm'
 
 export function getNewContract(
   id: string,
@@ -62,7 +64,7 @@ export function getNewContract(
 
 const getBinaryDpmProps = (initialProb: number, ante: number) => {
   const { sharesYes, sharesNo, poolYes, poolNo, phantomYes, phantomNo } =
-    calcStartPool(initialProb, ante)
+    calcDpmInitialPool(initialProb, ante, PHANTOM_ANTE)
 
   const system: DPM & Binary = {
     mechanism: 'dpm-2',
@@ -81,15 +83,13 @@ const getBinaryCpmmProps = (
   ante: number,
   userId: string
 ) => {
-  const { poolYes, poolNo, k } = calcStartCpmmPool(initialProb, ante)
+  const { poolYes, poolNo } = calcCpmmInitialPool(initialProb, ante)
   const pool = { YES: poolYes, NO: poolNo }
 
   const system: CPMM & Binary = {
     mechanism: 'cpmm-1',
     outcomeType: 'BINARY',
     pool: pool,
-    k,
-    liquidity: { [userId]: pool },
   }
 
   return system

common/payouts-fixed.ts

@@ -5,18 +5,32 @@ import { getProbability } from './calculate'
 import { deductFixedFees } from './calculate-fixed-payouts'
 import { Binary, CPMM, FixedPayouts, FullContract } from './contract'
 import { CREATOR_FEE } from './fees'
+import { LiquidityProvision } from './liquidity-provision'
 
-export const getFixedCancelPayouts = (bets: Bet[]) => {
-  return bets.map((bet) => ({
-    userId: bet.userId,
-    payout: bet.amount,
+export const getFixedCancelPayouts = (
+  contract: FullContract<FixedPayouts, Binary>,
+  bets: Bet[],
+  liquidities: LiquidityProvision[]
+) => {
+  const liquidityPayouts = liquidities.map((lp) => ({
+    userId: lp.userId,
+    payout: lp.amount,
   }))
+
+  return bets
+    .filter((b) => !b.isAnte && !b.isLiquidityProvision)
+    .map((bet) => ({
+      userId: bet.userId,
+      payout: bet.amount,
+    }))
+    .concat(liquidityPayouts)
 }
 
 export const getStandardFixedPayouts = (
   outcome: string,
   contract: FullContract<FixedPayouts, Binary>,
-  bets: Bet[]
+  bets: Bet[],
+  liquidities: LiquidityProvision[]
 ) => {
   const winningBets = bets.filter((bet) => bet.outcome === outcome)
 
@@ -44,20 +58,29 @@ export const getStandardFixedPayouts = (
   return payouts
     .map(({ userId, payout }) => ({ userId, payout }))
     .concat([{ userId: contract.creatorId, payout: creatorPayout }]) // add creator fee
-    .concat(getLiquidityPoolPayouts(contract, outcome))
+    .concat(getLiquidityPoolPayouts(contract, outcome, liquidities))
 }
 
 export const getLiquidityPoolPayouts = (
   contract: FullContract<CPMM, Binary>,
-  outcome: string
+  outcome: string,
+  liquidities: LiquidityProvision[]
 ) => {
-  const { creatorId, pool } = contract
-  return [{ userId: creatorId, payout: pool[outcome] }]
+  const providedLiquidity = _.sumBy(liquidities, (lp) => lp.liquidity)
+
+  const { pool } = contract
+  const finalPool = pool[outcome]
+
+  return liquidities.map((lp) => ({
+    userId: lp.userId,
+    payout: (lp.liquidity / providedLiquidity) * finalPool,
+  }))
 }
 
 export const getMktFixedPayouts = (
   contract: FullContract<FixedPayouts, Binary>,
   bets: Bet[],
+  liquidities: LiquidityProvision[],
   resolutionProbability?: number
 ) => {
   const p =
@@ -90,14 +113,21 @@ export const getMktFixedPayouts = (
   return payouts
     .map(({ userId, payout }) => ({ userId, payout }))
     .concat([{ userId: contract.creatorId, payout: creatorPayout }]) // add creator fee
-    .concat(getLiquidityPoolProbPayouts(contract, p))
+    .concat(getLiquidityPoolProbPayouts(contract, p, liquidities))
 }
 
 export const getLiquidityPoolProbPayouts = (
   contract: FullContract<CPMM, Binary>,
-  p: number
+  p: number,
+  liquidities: LiquidityProvision[]
 ) => {
-  const { creatorId, pool } = contract
-  const payout = p * pool.YES + (1 - p) * pool.NO
-  return [{ userId: creatorId, payout }]
+  const providedLiquidity = _.sumBy(liquidities, (lp) => lp.liquidity)
+
+  const { pool } = contract
+  const finalPool = p * pool.YES + (1 - p) * pool.NO
+
+  return liquidities.map((lp) => ({
+    userId: lp.userId,
+    payout: (lp.liquidity / providedLiquidity) * finalPool,
+  }))
 }

common/payouts.ts

@@ -2,6 +2,7 @@ import * as _ from 'lodash'
 
 import { Bet } from './bet'
 import { Contract, DPM, FreeResponse, FullContract, Multi } from './contract'
+import { LiquidityProvision } from './liquidity-provision'
 import {
   getDpmCancelPayouts,
   getDpmMktPayouts,
@@ -22,17 +23,23 @@ export const getPayouts = (
       },
   contract: Contract,
   bets: Bet[],
+  liquidities: LiquidityProvision[],
   resolutionProbability?: number
 ) => {
   if (contract.mechanism === 'cpmm-1' && contract.outcomeType === 'BINARY') {
     switch (outcome) {
       case 'YES':
       case 'NO':
-        return getStandardFixedPayouts(outcome, contract, bets)
+        return getStandardFixedPayouts(outcome, contract, bets, liquidities)
       case 'MKT':
-        return getMktFixedPayouts(contract, bets, resolutionProbability)
+        return getMktFixedPayouts(
+          contract,
+          bets,
+          liquidities,
+          resolutionProbability
+        )
       case 'CANCEL':
-        return getFixedCancelPayouts(bets)
+        return getFixedCancelPayouts(contract, bets, liquidities)
     }
   }
 

common/scoring.ts

@@ -1,4 +1,5 @@
 import * as _ from 'lodash'
+
 import { Bet } from './bet'
 import { Binary, Contract, FullContract } from './contract'
 import { getPayouts } from './payouts'
@@ -37,6 +38,7 @@ export function scoreUsersByContract(
     resolution ?? 'MKT',
     contract,
     openBets,
+    [],
     resolutionProbability
   )
 

functions/src/create-contract.ts

@@ -17,6 +17,7 @@ import { getNewContract } from '../../common/new-contract'
 import {
   getAnteBets,
   getCpmmAnteBet,
+  getCpmmInitialLiquidity,
   getFreeAnswerAnte,
   MINIMUM_ANTE,
 } from '../../common/antes'
@@ -127,7 +128,7 @@ export const createContract = functions
 
             const outcome = y > n ? 'NO' : 'YES' // more in YES pool if prob leans NO
 
-            const bet = await getCpmmAnteBet(
+            const bet = getCpmmAnteBet(
               creator,
               contract as FullContract<CPMM, Binary>,
               betDoc.id,
@@ -136,6 +137,19 @@ export const createContract = functions
             )
 
             await betDoc.set(bet)
+
+            const liquidityDoc = firestore
+              .collection(`contracts/${contract.id}/liquidity`)
+              .doc()
+
+            const lp = getCpmmInitialLiquidity(
+              creator,
+              contract as FullContract<CPMM, Binary>,
+              liquidityDoc.id,
+              ante
+            )
+
+            await liquidityDoc.set(lp)
           }
         } else if (outcomeType === 'FREE_RESPONSE') {
           const noneAnswerDoc = firestore

functions/src/resolve-market.ts

@@ -9,6 +9,7 @@ import { getUser, payUser } from './utils'
 import { sendMarketResolutionEmail } from './emails'
 import { getLoanPayouts, getPayouts } from '../../common/payouts'
 import { removeUndefinedProps } from '../../common/util/object'
+import { LiquidityProvision } from '../../common/liquidity-provision'
 
 export const resolveMarket = functions
   .runWith({ minInstances: 1 })
@@ -94,10 +95,19 @@ export const resolveMarket = functions
       const bets = betsSnap.docs.map((doc) => doc.data() as Bet)
       const openBets = bets.filter((b) => !b.isSold && !b.sale)
 
+      const liquiditiesSnap = await firestore
+        .collection(`contracts/${contractId}/liquidity`)
+        .get()
+
+      const liquidities = liquiditiesSnap.docs.map(
+        (doc) => doc.data() as LiquidityProvision
+      )
+
       const payouts = getPayouts(
         resolutions ?? outcome,
         contract,
         openBets,
+        liquidities,
         resolutionProbability
       )