Original practice scenario: An industrial-gas simulator records cylinder fills, customer deliveries, returns and maintenance. Explain how to calculate available cylinders by location.
Read model answer +
Count physical assets by their accepted current state, not by summing movement rows. Availability also depends on inspection and maintenance status, so location alone is insufficient.
Work through it
Assign each cylinder a stable identifier and order accepted state-changing events using source sequences and explicit correction rules.
Derive one state per cylinder at the cutoff, preserving contents, location and inspection eligibility; quarantine impossible transitions or conflicting simultaneous locations.
Aggregate eligible states by location and cylinder class, then reconcile the fleet total including customer-held, in-transit and maintenance units.
Tradeoffs to discuss
Event histories support audit and historical views; materialized current-state tables speed queries but require reliable rebuilding and reconciliation.
Common pitfalls
Do not count a duplicate return as another cylinder.
An empty cylinder and an available filled cylinder are different inventory categories.
Original practice scenario: A hypothetical industrial-gas distributor proposes delivery routes with vehicle capacities, service windows and incompatible cargo classes. How should a route validator work?
Read model answer +
Separate feasibility checking from route optimization. A fast heuristic can propose useful routes, but a deterministic validator must reject any plan that violates the declared synthetic constraints.
Work through it
Represent capacities and demands in consistent units, validate cargo compatibility, and propagate arrival and service times through each stop.
Track load changes after deliveries and collections, incorporating required breaks or return legs only when included in the exercise's explicit model.
Test boundary capacities, waiting before a service window, impossible time windows, duplicate stops and omitted orders; return specific violated constraints.
Tradeoffs to discuss
Exact optimization may become expensive, while heuristics scale better with no guarantee of optimality; feasibility remains independently testable.
Common pitfalls
Do not describe the shortest-distance route as automatically feasible.
Keep real transport safety and operating rules outside unvalidated classroom assumptions.
