0-3-4-understand-a008

name	0.3.4-understand-a008
description	["0.3.4"]
Threshold in agreement	the minimum number of correct processes required to guarantee safety and liveness unde

understand-a008

CALL NUMBER: deep_raft.a008 : distributed_consensus_and_replication_protocols(3) DEFINITION: Threshold in agreement: the minimum number of correct processes required to guarantee safety and liveness under given failure assumptions.

Invoke this skill to understand a008 down to its primitives. The RELATIVE ROOT below is the least-fixed-point closure of everything it bundles from — the full import cone, grouped by the lib each prim comes from. Projected from a prover-typed KB (MAP/SWI-Prolog consistency gate): every reference below resolves.

THE RELATIVE ROOT (the import cone, by lib)

from ?

• agreement (d3): The property that a set of distributed processes reach the same decision outcome on a given value. Uniform agreement requires all processes including those that later crash to decide identically; asymmetric agreement permits different decision classes for different process roles such as primary versus backup.

from deep_raft

• a009 (d1): Asymmetric agreement: one class of processes (e.g., primary) must agree while another class (e.g., backups) may reach different decisions, used in primary-backup protocols.
• a005 (d2): Uniform agreement: all processes including those that later fail must decide on the same value, stricter than ordinary agreement which only binds correct processes.
• a007 (d3): Quorum in agreement: a subset of processes sufficient to guarantee agreement can be reached, typically intersecting any valid quorum to ensure overlap.
• a002 (d4): Validity in agreement: the decided value must have been proposed by some process in the system, guaranteeing agreements are grounded in actual proposals.
• a004 (d5): Termination in agreement: every correct process eventually decides some value, ensuring the protocol makes progress and does not stall indefinitely.

from distributed_consensus_and_replication_protocols

• replicated_log (d1): Ordered log of commands maintained across replicas; foundation of state machine replication.
• consensus (d2): Agreement on a single value among a set of distributed processes; the core problem consensus protocols solve.
• fault_tolerance (d3): System's ability to continue operating correctly despite component failures.

CONSUMERS (what needs this)

consensus, ft013

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Projected from the distributed consensus and replication protocols KB (196 concepts / 187 relations) — consistency-typed by MAP; the facet list after the colon IS the cross-lib dependency web.

(leaf — this is an actual skill.)