Pearson Edexcel IAL D1 Decision Mathematics Notes

D1 Decision Mathematics 1 is an IAS applied unit in Pearson Edexcel International A Level Mathematics. It covers algorithms, networks, project planning and linear programming. For the full Mathematics award, D1 can be paired with M1 Mechanics 1 or S1 Statistics 1, alongside compulsory P1 to P4.

Use this page as an independent revision note for the current Issue 3 specification. It is not Pearson's solution bank or a reproduced mark scheme. D1 can also be used in some Further Mathematics routes, but the qualification rules and result use are separate.

Official unit scope

1. Algorithms and graph terminology.
2. Minimum spanning trees and shortest paths.
3. Route inspection and travelling-salesperson bounds.
4. Critical path analysis.
5. Linear programming and simplex ideas.
6. Sorting, packing and matching algorithms.

Where D1 fits

• Level: IAS applied unit.
• Full IAL Mathematics routes: M1 + D1 or S1 + D1.
• Revise first: graph terminology, inequalities, coordinate geometry and careful tabular working.
• Different award: if you are taking D1 for Further Mathematics, use the Further Mathematics D1 route note.

The specification assumes prerequisite knowledge stated for the unit, so later-unit questions may combine earlier methods without re-teaching them. Treat the list above as an integrated toolkit. A question can begin in one topic and finish in another, such as using algebra to form a model, calculus to optimise it and a graph to interpret the result.

Core reasoning and methods

• Follow an algorithm's tie-breaking and labelling rules visibly so the final answer can be audited.
• Distinguish a minimum spanning tree, which connects all vertices cheaply, from a shortest path between two named vertices.
• In critical path analysis, use forward and backward passes to identify zero-float activities and project duration.