What is sequential dependencies?

Example: You are planning a cross-country move. Some tasks are independent: researching neighborhoods, getting insurance quotes, and selling furniture can all happen at the same time, handled by different people or by you in any order. But other tasks have hard dependencies: you cannot schedule the movers until you have signed a lease, and you cannot sign a lease until you have chosen a city. If you try to do everything sequentially — finish one task completely before starting the next — the move takes months longer than it needs to. If you try to do everything in parallel — including the tasks with dependencies — you waste effort on quotes for cities you will not choose and schedules for apartments you have not secured. The skill is not choosing parallel or sequential. It is mapping which tasks depend on which, running the independent ones simultaneously, and sequencing only the ones that genuinely require prior results.

This concept is part of Multi-Agent Coordination in the How to Think curriculum.