Fault-tree & event-tree analysis

Builds a fault tree per deviation with AND/OR boolean logic to get the combined top-event probability plus every minimal cut set, and an event tree that branches an initiating event through successive safety functions to enumerate all outcome probabilities — the logic behind a failure or a consequence sequence, not just a single number.

• A deviation's cause structure is genuinely AND/OR (multiple simultaneous failures needed) rather than a single credited IPL.
• You need to show which combination of failures (a minimal cut set) actually drives the top event, to target the cheapest fix.
• Tracing how an initiating event can end in different consequences depending on which safety functions do or don't work.

The fault tree evaluates its boolean gate structure bottom-up to a single top-event probability and enumerates minimal cut sets (the smallest failure combinations that alone cause the top event); the event tree enumerates all 2^k outcome paths for k branch points, each with its combined probability.