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CRON Theorem

Last updated Aug 12, 2022 Edit Source

Causality Required Only for Non-monotonicity (CRON).

Eventual consistency can be guaranteed in any program by protecting non-monotonic statements (“points of order”) with consensus protocols

Rephrased: Program semantics require causal message ordering if and only if the messages participate in non-monotonic derivations (e.g. set removal)

See also: CALM Theorem