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Short note: Distributed cut

Short answer

A distributed cut is a prefix of each process's history, representing a global state. A consistent cut includes all events that happened before any included event, so no message is received whose send is outside the cut. Inconsistent cuts violate this, making them impossible states. Consistent cuts are used in snapshots and debugging.

Write a short note on distributed cut.

A distributed cut is a set of events, taking a prefix of the history of each process, that represents a possible global state. Its boundary (a line across the process time-lines) is called the cut frontier.

  • Consistent cut: if an event e is in the cut, every event that happened before e is also in it. No message is received inside the cut while its send lies outside. It represents a state the system could really have been in.
  • Inconsistent cut: includes a receive event without its send, so it cannot occur in real execution.

Consistent cuts are used in checkpointing, snapshot algorithms (Chandy-Lamport), deadlock and termination detection, and debugging.

✓ Answer checked by Claude Opus 5.5 (high effort)

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