$$ \newcommand \TP {\mathrm{TransactionPool}} \newcommand \Next {\mathit{next}} \newcommand \Late {\mathit{late}} \newcommand \Redo {\mathit{redo}} \newcommand \Down {\mathit{down}} $$

Examples of Protocol Runs

The following section presents three examples of valid protocol runs, going from simple to more complex agreement attempts, by adding partition scenarios that involve recovery stages.

The run examples are named from “best” to “worst” respectively:

• Vanilla Run: agreement is achieved at the first attempt,

• Jalapeño Run: agreement is achieved with a \( \Next \) recovery procedure,

• Habanero Run: agreement is achieved with \( \Late, \Redo, \Down \) fast recovery procedure.

Besides being the simplest, the Vanilla Run is the most common case, as infrastructure failures are extremely rare. However, the partition scenarios in the Jalapeño Run and Habanero Run shed light on the recovery mechanisms.

Initial Context

All three scenarios share the following initial context and are played by the node \( \bar{N} \).

A genesis block was generated. Algorand has been running for a while with a set of nodes and accounts, and several blocks have already been generated.

The network is now at round \( r - 1 \) (with \( r >> 2 \)), meaning that \( r - 1 \) blocks have been generated and confirmed on the blockchain.

Moreover, the node \( \bar{N} \) has:

• Received some transactions,

• Verified them to be correctly signed by Algorand accounts,

• Validated them according to Ledger and node context,

• Added them to its \( \TP \),

• Relayed them to other nodes.

For this section, we assume that all players behave according to protocol and are in sync, that is:

• The context \( (r, p, s) \) for all nodes is the same,

• Nodes’ internal clocks are synchronized.