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description: atlETH bonding mechanism
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# Altas Bonding Concept

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Solvers are required to bond atlETH (POL) from the EOA which is used to submit solverOperation to cover the transaction cost before solution can be executed\
[Bond ](https://polygonscan.com/address/0x912AceADa1b9c9B378894D0610C5684167710FDD#writeContract)[POL](https://polygonscan.com/address/0x912AceADa1b9c9B378894D0610C5684167710FDD#writeContract)
{% endhint %}

## atlETH

atlETH serves as a wrapped representation of the blockchain's native token within Atlas. While named "atlETH" for simplicity, it represents the native token of whichever blockchain Atlas is deployed on (e.g., ETH on Ethereum, POL on Polygon). This mechanism enables solvers to escrow funds for their gas consumption, allowing them to pre-commit to covering the gas costs for their respective operations.

By using atlETH, Atlas facilitates the execution of transactions that include multiple third-party SolverOperations by bundlers. Additionally, it discourages solver spam by leveraging the DoS protection inherent in the underlying chain's gas costs.

### Key Features and Mechanics

1. **Balance Verification**: The Operations Relay (OR) and/or Atlas SDK are responsible for verifying the solvers' atlETH balance.
2. **Intrablock Participation Limit**: At the smart contract level, Atlas restricts solvers from participating in more than one auction per block. This prevents double-counting of bonded atlETH across multiple applications and bundlers.
3. **Penalty for Multiple Executions**: Any attempt by solvers to execute a second operation in the same block will result in a reverted operation, with solvers still incurring charges for their total gas costs.
4. **Multiple Intrablock Auctions**: To engage in multiple intrablock Atlas auctions, solvers must use separate EOAs and maintain bonded atlETH balances in each.

### Solver Responsibilities

**Known Bids Mode**

In known bids mode, the solver is responsible for approving payment for the sum of:

* The gas cost of the transaction so far, excluding costs attributed to reverted operations of other solvers.
* The gas cost remaining in the transaction up to the gas limit.
* The outstanding balance of any cross-operation flash loan initiated by the hooks.

### atlETH Escrow Process

1. An escrow hold is placed on the solver's bonded atlETH balance for the total estimated amount owed.
2. The Atlas smart contract adjusts this escrow at the end of the transaction based on actual gas consumption.
3. Solvers can estimate the gas limit and value of the Atlas transaction before signing their operation, allowing them to anticipate the required escrow amount.

<figure><img src="https://4266440485-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcdwawPu1WZY0iOUAGHRD%2Fuploads%2FNUyyuLw1GcV18n28C0y4%2Faleth-escrow.png?alt=media&#x26;token=49be0a64-2e9c-4f3e-a344-7a27a9b226cb" alt=""><figcaption></figcaption></figure>

### Protection Against Malicious Actors

Solvers are not liable for their gas costs if they are under attack by malicious originators, auctioneers, or bundlers. An altered UserOperation or CallChainHash will attribute any accrued solver gas costs to the bundler.

### Disincentivizing Large Gas Limits

To discourage bundlers from setting excessively large gas limits (which would force solvers to maintain higher escrow balances), Atlas estimates the excess gas limit and charges the bundler for it during gas accounting.



