Linearizability

Operations appear atomic at an instant; real-time order is preserved

MARKO ŽIVKOVIĆ In review

Linearizability (Herlihy & Wing) is a consistency guarantee for concurrent objects: each operation appears to take effect atomically at a single instant between its invocation and response, and real-time order is preserved — if operation A completes before B begins, A’s effect is visible before B’s.

A multi-stream view that is linearizable at wall time T is one a closed-loop controller, trading engine, or L1 invariant enforcer may treat as a true simultaneous cut. It is stronger than serializability, which does not require alignment with wall-clock order.

When it matters

Context	Typical need
Robotics, motion control, safety interlocks	Linearizable cut — sub-ms mismatch can be catastrophic
Fraud / balance enforcement (Class A)	Linearizable or equivalent single-writer stream
Enterprise dashboards	Often not linearizable; disclose lower guarantee

Linearizability implies low cross-stream consistency uncertainty only when the producer declares and enforces it. Timestamps plus bounded clock skew approximate a cut for many reads; they do not automatically imply linearizability.

Corpus stance

A2 — working context: Formal DS vocabulary for the strongest common read guarantee in the uncertainty contract. See Why Uncertainty Matters.