$$ \newcommand \Cert {\mathit{cert}} \newcommand \Next {\mathit{next}} \newcommand \DeadlineTimeout {\mathrm{DeadlineTimeout}} \newcommand \Vote {\mathrm{Vote}} \newcommand \Bundle {\mathrm{Bundle}} $$

Recovery

On observing a timeout event of

• \( T = \DeadlineTimeout(p) \) or

• \( T = \DeadlineTimeout(p) + 2^{s_t}\lambda + u \) where \( u \in [0, 2^{s_t}\lambda] \) sampled uniformly at random,

the player attempts to resynchronize and then broadcasts* \( \Vote(I, r, p, \Next_h, v) \) where

• \( v = \sigma(S, r, p) \) if \( v \) is committable in \( (r, p) \),

• \( v = \bar{v} \) if there does not exist a \( s_0 > \Cert \) such that \( \Bundle(r, p-1, s_0, \bot) \) was observed and there exists an \( s_1 > \Cert \) such that \( \Bundle(r, p-1, s_1, \bar{v} )\) was observed,

• and \( v = \bot \) otherwise.

⚙️ IMPLEMENTATION

Next vote issuance reference implementation.

Next vote timeout ranges computation reference implementation.

Call to \( \Next_0 \) reference implementation.

Subsequent calls to \( \Next_{st} \) reference implementation.

Step increase in recovery step timeouts reference implementation.

For a detailed overview of how the recovery routine may be implemented, refer to the Algorand ABFT non-normative section.

In other words, if a proposal-value \( v \) is committable in the current period,

$$ N(S, L, t(T, p)) = (S’, L, (\ldots, \Vote(I, r, p, \Next_h, v))); $$

while in the second case,

$$ N(S, L, t(T, p)) = (S’, L, (\ldots, \Vote(I, r, p, \Next_h, \bar{v}))); $$

and otherwise,

$$ N(S, L, t(T, p)) = (S’, L, (\ldots, \Vote(I, r, p, \Next_h, \bot))). $$