Calculate which task can actually advance the launch

Define a calculable dependency contract

PMI’s critical-path paper describes forward and backward passes and total float. Here resources are independently feasible, durations deterministic, dependencies finish-to-start, and lags absent.

Ask the owners to confirm what completion means for each activity before assigning a duration. A file being uploaded might not satisfy the condition that allows the next stage to begin. Keep this acceptance question separate from the mathematical calculation: an accurately computed network cannot repair an incorrect description of the work.

Use a small synthetic network to make the reasoning visible. Record the unit of time and the start convention. Do not copy a supplier’s proposed dates into duration fields without checking what those dates include. Keep unresolved assumptions visible and avoid presenting the result as an externally agreed commitment.

Work forward to the finish

Fictional durations in days: brief 2; then copy 4 and art 3; proof 2 after both; release 1. Brief finishes at 2, copy at 6, art at 5. Proof waits for max(6, 5), then finishes at 8; release finishes at 9.

Write the predecessor requirement beside each activity rather than relying on its position in a list. The visual order of a spreadsheet can imply a sequence that the actual work does not require. Conversely, a missing dependency can make an attractive date appear achievable even though an essential input is unavailable.

Have another reviewer reproduce the result from the stated relationships. Ask them which assumption they would challenge operationally, not just whether the additions are correct. If the activities compete for the same specialist or equipment, the stipulated independent-resource model no longer settles the feasible schedule. Route that issue to the responsible planner rather than quietly reusing the original result.

Work backward and test the proposed shortcut

Working backward from 9, release starts at 8 and proof at 6. Art may start at 3, versus earliest 2: float 1. Copy must start at 2. Brief finishes by min(2, 3) = 2. Zero-float path: brief, copy, proof, release. Shortening art by 1 leaves finish 9. Shortening copy by 1 makes both branches finish at 5 and launch at 8: tied paths.

Compare these alternatives as separate changes to the original network. Do not apply the second change to a version that already contains the first unless the proposal explicitly calls for both. Preserve the unchanged inputs so the owner can see why an apparently similar effort produces a different result.

Ask what it would take to deliver the proposed shorter activity without changing its acceptance standard. Extra cost, a different reviewer or reduced scope may require additional approval. The mathematical comparison does not establish that acceleration is feasible, beneficial or authorized. If the proposed shortcut removes necessary review, stop at that conflict and seek a legitimate alternative.

Present the consequence rather than a label

Show the original network, the proposed change and the resulting finish together. Explain the operational assumption that makes the alternative possible. A highlighted critical label is less useful than a reproducible explanation of which required input controls the next stage in this particular plan.

Keep the calculated result separate from calendar commitments. Holidays, actual resource availability and external approvals may still need a qualified scheduling review. If those constraints are material, do not translate the illustration directly into a promised launch date. State what remains to be established before a real commitment can be considered.

When a duration or dependency changes, preserve the earlier version and calculate the revised plan rather than defending the original highlight. A network is a representation of agreed assumptions, not a guarantee that the work will unfold exactly as drawn. Close with a recommendation for the authorized owner: which proposed acceleration merits investigation, what evidence is missing and what tradeoff the owner would need to accept.

Make the reasoning concrete.

A fictional campaign lead offers to rush artwork because it is the most visible unfinished item. The team compares that proposal with an independently considered copy improvement using the network above.

The team investigates the proposal that changes the result, without changing a deadline, buying extra services or waiving approval.

Take the questions into your next brief.

Use these prompts in your own notes. Nothing is submitted from this page.

1. Contract

   What completion condition does each successor require?

2. Assumptions

   Are the stated resources and durations appropriate for this model?

3. Forward

   Can the finish be reproduced from the dependencies?

4. Alternative

   What single change is being compared with the original?

5. Authority

   What evidence and approval are required before implementation?

Watch for the wrong conclusion.

• Mistaking list order for an agreed dependency.
• Applying several changes while attributing the result to only one.
• Treating mathematical acceleration as authorization to weaken review.

Sources & scope

Original explicitly fictional traces and activity networks. Method definitions and calculation applications remain source-derived. No future guarantee, personnel assessment, scheduling change or purchase is made. Qualified owners review operational feasibility.

• PMI: Critical path method calculations →Primary teaching material · Supports: Supports the scheduling calculations.