durin •

A framework for building solvers for the OP Stack's dispute protocol.

Overview

• durin-primitives - Contains primitive types and traits used by other solvers within durin as well as agents utilizing the solvers.
• durin-fault - Contains an implementation of a solver for Optimism's FaultDisputeGame.

What's a Solver?

The OP Stack contains a dispute protocol that allows developers to implement Dispute Games, simple primitives that allow the creation of a Claim, a 32-byte commitment to a piece of information, and a method to resolve this Claim to true or false.

A Dispute Game has many possible implementations - for Optimism's purposes, the primary usecase for such a game is to dispute claims about the state of an OP Stack chain on L1. The solution for this was the FaultDisputeGame, an implementation of a Dispute Game that allows participants to bisect an instruction trace to find the exact instruction that they and their opponent diverge, and execute a single instruction on-chain via an emulated VM (such as MIPS for Cannon or RISC-V for Asterisc) to prove their opponent wrong.

This is only one possible implementation of a Dispute Game - the OP Stack's dispute protocol allows for arbitrary implementations of this primitive. The durin framework allows developers to create solvers for their own implementation of a Dispute Game and use them within simulations, challenge agents, testing, and more.

Creating a Solver

1. Create a new crate for your solver under the crates directory.
2. Add durin-primitives as a dependency to your crate.
   1. Implement the DisputeGame trait to model the state of your dispute.
   2. Implement the DisputeSolver trait on your solver struct.
   3. Create Rules for your solver.

What's a Rule?

A Rule is an isolated invariant check on a DisputeGame's state that can be used to determine if a solver's suggested state transitions hold the state's invariants. The durin-primitives trait exports the Rule type as well as the chain_rules macro, which can be used to apply multiple rules on top of each other when asserting pre or post conditions for the game's state transitions.

As the solvers within durin are meant to be consumed by agents who act on their suggestions, it is critical that the state invariants of the respective games are upheld. Rules allow developers to easily define the expected behavior of the state transitions, check their invariants, and assert that their solver's suggestions are valid with respect to the state's invariants.