Lux Docs

Automated Market Makers - V2 constant-product, V3 concentrated liquidity, and StableSwap

The AMM module provides three pool types for different trading scenarios. All AMM contracts are in contracts/amm/.

V2 (Constant Product)

Classic x * y = k AMM based on Uniswap V2. Best for long-tail token pairs.

Contract	Import
AMMV2Factory	`@luxfi/contracts/amm/AMMV2Factory.sol`
AMMV2Pair	`@luxfi/contracts/amm/AMMV2Pair.sol`
AMMV2Router	`@luxfi/contracts/amm/AMMV2Router.sol`

import "@luxfi/contracts/amm/AMMV2Router.sol";

AMMV2Router router = AMMV2Router(ROUTER_ADDRESS);

// Add liquidity
router.addLiquidity(
    tokenA, tokenB,
    amountADesired, amountBDesired,
    amountAMin, amountBMin,
    to, deadline
);

// Swap exact tokens for tokens
router.swapExactTokensForTokens(
    amountIn, amountOutMin,
    path, to, deadline
);

V3 (Concentrated Liquidity)

Uniswap V3-style concentrated liquidity. LPs provide liquidity within specific price ranges for higher capital efficiency.

Contract	Import
AMMV3Factory	`@luxfi/contracts/amm/AMMV3Factory.sol`
AMMV3Pool	`@luxfi/contracts/amm/AMMV3Pool.sol`

Fee tiers: 0.01% (1 tick), 0.05% (10 ticks), 0.3% (60 ticks), 1% (200 ticks).

import "@luxfi/contracts/amm/AMMV3Factory.sol";

AMMV3Factory factory = AMMV3Factory(FACTORY_ADDRESS);

// Create pool with 0.3% fee
address pool = factory.createPool(tokenA, tokenB, 3000);

StableSwap (Curve-Style)

Optimized for pegged assets (stablecoins, wrapped tokens) using the StableSwap invariant. Supports 2-4 token pools with minimal slippage between like-kind assets.

Contract	Import
StableSwap	`@luxfi/contracts/amm/StableSwap.sol`
StableSwapFactory	`@luxfi/contracts/amm/StableSwapFactory.sol`

The amplification coefficient A controls pool behavior -- higher values produce tighter peg, lower values behave more like constant-product.

import "@luxfi/contracts/amm/StableSwap.sol";

StableSwap pool = StableSwap(POOL_ADDRESS);

// Swap token index 0 for token index 1
uint256 dy = pool.exchange(0, 1, dx, minDy);

// Add liquidity (balanced or imbalanced)
uint256 lpTokens = pool.addLiquidity(amounts, minMintAmount);

// Remove liquidity in a single token
uint256 received = pool.removeLiquidityOneCoin(lpAmount, tokenIndex, minAmount);

StableSwap Invariant

A * n^n * sum(x_i) + D = A * D * n^n + D^(n+1) / (n^n * prod(x_i))

Pool D is computed iteratively using Newton's method with guaranteed convergence in under 255 iterations.

Dynamic A Parameter

The amplification coefficient can be ramped over time (minimum 24-hour ramp period) to adjust pool characteristics without redeployment:

// Ramp A from current value to 500 over 48 hours
pool.rampA(500, block.timestamp + 48 hours);

Fee Structure

Pool Type	Swap Fee	Admin Fee
V2 Pair	0.3%	Protocol-defined
V3 Pool	0.01% - 1%	Per fee tier
StableSwap	0.04%	50% of swap fee