$$ \newcommand \Soft {\mathit{soft}} \newcommand \Cert {\mathit{cert}} \newcommand \Next {\mathit{next}} $$

Resynchronization Attempt

The resynchronization is an auxiliary function used throughout the recovery steps.

A partial order relation is defined in the space of all observed bundles. We call this relation freshness.

A resynchronization attempt broadcasts the freshest observed bundle (if any).

Priority-wise, bundles’ freshness is defined as follows:

• Bundles for a \( \Cert \) step are fresher than all other bundles.

• Bundles from a later period are fresher than bundles from an older period.

• Bundles for \( \Next \) step are fresher than bundles for a \( \Soft \) step of the same period.

• Bundles for \( \Next \) step for the \( \bot \) proposal-value are fresher than bundles for a \( \Next \) step for some other value.

For a formal definition of this property, refer to the ABFT normative section.

⚙️ IMPLEMENTATION

Bundle freshness reference implementation.

In the reference implementation, a resynchronization attempt is handled by the partitionPolicy function, as the network is assumed to be in a “partitioned state” due to the temporary inability to reach consensus. In this case, the function is only invoked when the current step \( s \geq 3 \) or when the current period \( p \geq 3 \) (that is, the player has gone through two full periods without reaching a consensus).