horse.pair
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How it works

horse.pair in plain words and a few drawings. A pari-mutuel board of forty-two horses, kept by a Uniswap v4 hook. Ten short parts.

01

The idea

Forty-two horses, one pot. The odds are a quotient, nobody sets them. The horse nobody backed wins.

One board, shared, whose state lives in a Uniswap v4 hook. Forty-two horses, numbered 01 to 42. You stake $HORSE on one of them. There is no bookmaker: all the money goes into one pot, and the odds of each horse are computed, not fixed. The race is measured in swaps on the pool, and when it reaches the post, the horse whose share of the pot was the lowest on average wins. Its holders share the pot.

A swap on the pool buy or sell, it does not matter The race moves one step and 70% of the fee drops in the pot A ticket stake on one horse Its odds fall for everyone on it, you included The pot locked until the post At the post the least backed horse wins, its holders share the pot
Nobody triggers anything. The arrival happens inside the swap that reaches the post, and the board empties for the next race.

The whole thing rests on a paradox every bettor knows without having said it: being right is worth nothing if everyone is right at the same time. That is not a rule we added. It is the arithmetic of the pari-mutuel, the mechanism invented by Joseph Oller in 1867.

02

The odds

The odds of a horse are the pot divided by what is staked on it. One division of two public numbers, shown with two decimals.

That one number is three things at once: a price, what one unit of exposure to this horse costs; an implied probability, since one over the odds is the horse's share of the pot; and a payout, what one unit returns if this horse wins. It is not set by anyone and it is not a prediction. The contract has no opinion: it divides.

Horse 31, before and after your ticket before 4,198 staked 286.97 after 14,198 staked, your 10,000 included 85.55 pot 1,204,700 ÷ 4,198 = 286.97, then pot 1,214,700 ÷ 14,198 = 85.55 Your own ticket divided the odds by more than three, for you and for everyone already on it.

There is no way to stake without diluting yourself. That is the founding constraint of the pari-mutuel, it is arithmetic, and no parameter can soften it. The favourite is the most backed horse: lowest odds, smallest payout, and here, the one least likely to win. The outsider is the least backed: highest odds, and the one that wins if it stays that way.

03

Who wins

The horse whose share of the pot was, on average over the whole distance, the lowest.

Not the odds at the post. The average, step by step, from start to finish. On a real racecourse the big money arrives in the last seconds, the odds collapse at the start, and the early bettors on a 40-to-1 outsider watch their payout fall to 12 without having done anything. Here that is useless by construction: a massive ticket on the last step changes almost nothing to the average of a horse that was ignored for 4,199 steps.

Share of the pot, step by step another horse, steady, about 2% of the pot horse 31, ignored for almost the whole race the crowd arrives late distance, in swaps Average over the race: 31 stays far below. It wins. The late rush bought almost nothing.

So to win, a horse has to have been the outsider for a long time, not for a second. Staking early is worth more than staking late, twice: the odds are better, and a ticket weighs on every step left in the race. And you want nobody to follow you. The day your horse becomes obvious, it stops being the outsider, and it loses.

When the two lowest averages are closer than one ten-thousandth, the board shows a photo-finish and settles on the share at the post. A carved rule, with no randomness, that will almost never happen.

04

The distance

A race is counted in swaps on the pool, not in minutes, not in blocks, not in dates.

The post is at 4,200 swaps at level one, and ten percent further every time the payout record is broken. The race on the board is at level three: its post is at 5,082. A nervous market runs short races and frequent payouts. A calm market runs a long race and a pot that grows. And a dead market pauses the race, it does not kill it: no ticket is erased, no average is distorted, and it restarts at the next swap.

3,180 of 5,082 swaps, level 3 last turn 1,902 swaps to go. One fewer at every swap, and anybody can check it. The last five percent change no rule. They raise the fee to its ceiling, and they are the moment the pot grows fastest. The windows never close: you can stake and withdraw until the last step. The average makes the latecomer harmless instead.
05

Five moves

  • 1
    Swap.Automatic, through the hook. Every trade on the pool moves the race one step and feeds the pot. The direction plays no part.
  • 2
    Stake a ticket.Pick a horse, put $HORSE on it. Its odds fall for everyone, you included. A ticket staked early weighs on every step left.
  • 3
    Withdraw a ticket.Allowed until the last step. The horse's odds rise back for everyone. But a withdrawn ticket is out of the race: it does not share the pot, even if its horse wins. Withdrawing is giving up.
  • 4
    The post.Not a move. It happens inside the swap that reaches the distance. Nobody triggers it, nobody is paid to.
  • 5
    Cash in.If your horse won, your part of the pot is yours to collect, weighted by your stake and by the distance your ticket carried.
06

The fee

Five steps, by the distance run. The same for a buy and a sell. Nothing else enters it.

0.8%0 to 25% 1.2%25 to 50% 1.8%50 to 75% 2.6%75 to 95% 4.0%the last turn 4% is the ceiling, a constant, not a setting

The fee rises because the end is when the pot has to fill fastest: the outcome takes shape, attention is highest, and each step counts more than the first thousand. It is symmetric because the distance is a counter of events, and a counter does not know what a buy is. The liquidity providers' own fee is untouched; the two add up, and the total is shown as one number before you sign.

Of each fee
70%

goes to the pot. Every trade on the pool grows the prize, even from traders who never looked at the board.

Of each fee
30%

is burned. Nothing to a team. Two lines, the simplest split there is.

07

The pot and the levy

The pot is bigger than what the bettors staked. The levy is 15%, carved, and shown at the top of the board like on any racecourse.

Where the pot comes from Stakesall of them Fees70% of each swap fee Carry10% of the last pot The pot1,204,700 At the post, after the 15% levy is read off the top 85% to the holders of the winner 10% 10% carried to the next race, 5% burned, 0% to a team payout = pot × 85% ÷ the weighted stakes on the winner, announced as "X for 1" Race 47: 243.92 for 1. 117 winning tickets out of 3,481.

A classic operator keeps about a quarter before the race starts, up to a third on some bets. Here it is fifteen percent, and the number sits at the top of the board, not in the terms. That is not a performance, it is the absence of a middleman. The pot is locked until the post: there is no function to open it, no vote, no manual call.

Holders of the winner share by stake times distance carried. A ticket staked at step 100 carried almost the whole race; one staked at step 4,982 carried a hundred steps. At equal stake, the first collects close to fifty times more.

08

What it cannot do

  • 1
    It never refuses a swap.No condition, ever. The windows never close, and no action is ever blocked.
  • 2
    It cannot stop a pool without the hook.Anyone can open one. Those swaps do not move the race and do not feed the pot, so the bypass only interests somebody who is not playing, and the leak shows at once: the distance would stop moving while volume shows elsewhere.
  • 3
    It cannot change the levy, the fee steps or the split.Constants. No owner, no pause, no blacklist, no proxy.
  • 4
    It cannot stop one player from backing several horses.It can only make them pay for each ticket.
  • 5
    It cannot be sniped at the last block.No bonus to the swap that crosses the post, no bonus for noticing the arrival, and the average makes the last ticket almost weightless.
09

The flaw

This is a bet, and the word is the right one. Here is what that costs, with numbers.

At every race
41 of 42

horses lose their stakes. The pot of the losers is the payout of the winners. There is no other honest way to say it.

Race 47
3 in 100

117 winning tickets out of 3,481. The other 97 lost their stake, and their money made the 243.92 for 1.

After the levy
−15%

a closed economy, negative after the levy. Nothing comes from outside except the pool's fees.

Big payouts and rare winners are the same fact. The protocol cannot produce small payouts, because the winner is by definition the least backed horse, so the pot is by definition shared by few. Being right too visibly is losing: a strategy everyone knows stops winning the day it is known.

The vector that stays open

Someone who sees the end coming can stake on the horse leading the average, knowing a late ticket barely dents it. A free ride on the last stretch. It is bounded because that ticket still dilutes the payout, so it penalises itself, but it is real and it is named here.

And one thing that is not a flaw

A dead market does not end a race. Without swaps the board freezes, the odds stay, nothing happens. That is a pause, not decay. The protocol waits, and restarts exactly where it was.

10

A few words

HorseOne of the forty-two lines of the board, numbered, nameless.
TicketA stake on one horse. Staked early it weighs more; withdrawn, it is out of the race.
PotStakes, plus 70% of every swap fee, plus the carry. Locked until the post.
StakedThe sum of the forty-two stakes. Shares are computed on it, not on the pot.
OddsPot divided by the stakes on a horse. A price, a probability and a payout in one number.
ShareStakes on a horse divided by all stakes. The forty-two shares add up to one.
DistanceThe number of swaps since the start. The post is at 4,200 at level one, ten percent further per record.
The last turnThe final five percent. Fee at its ceiling, board in red.
LevyFifteen percent of the pot, read off the top at the post. Always shown.
PayoutWhat one unit staked on the winner returns, announced as "X for 1".
Never "yield", never "APR", never "invest". You stake, you hold a ticket, you collect a payout. A strategy that everyone knows stops winning the day it is known, so there is no winning strategy to publish, and none is.