1

Using Interaction matrices for requirements analysis

Objective – to discover the interactions between requirements and to highlight requirements conflicts and overlaps.

Tool – spreadsheetRows – label the requirement identifiers in ascending orderColumns – label the requirement identifiers also in ascending order

Each requirement is then considered and compared with other requirements. You then fill in values in the spreadsheet cells as follows:

1.If conflict, fill in 12.If overlap, fill in a 10003.If independent, fill in a 0

2

Situations:

If you cannot decide whether requirement conflict, assume yesWhy?

Interaction matrices example

Requirement R1 R2 R3 R4 R5 R6R1 0 0 1000 0 1 1R2 0 0 0 0 0 0R3 1000 0 0 1000 0 1000R4 0 0 1000 0 1 1R5 1 0 0 1 0 0R6 1 0 1000 1 0 0

R1 overlaps R3R1 conflicts with R5 and R6R2 is an independent requirementR3 overlaps with R4 and R6…

3

Number of conflicts = 3000 % 1000 = 0Number of overlaps = (int) 3000 / 1000 = 3

A large number of conflicts or overlaps means that any changes to thatrequirement will probably have a major impact on the rest of the system.

Requirement R1 R2 R3 R4 R5 R6R1 0 0 1000 0 1 1R2 0 0 0 0 0 0R3 1000 0 0 1000 0 1000R4 0 0 1000 0 1 1R5 1 0 0 1 0 0R6 1 0 1000 1 0 0

1002 0 3000 1002 2 1002

4

Requirements Analysis and NegotiationVideo game minimum system requirements

R1. Video card memory shall be at least 256M R2. Video card memory speed shall be at least 800MHz R3. Video card interface type shall be AGP R4. The video game shall be installed in 32-bit architecture system. R5. Monitor resolution shall be at least 1024x768pixel R6. Motherboard video card slot shall be PCIe R7. Input device shall be a three-button mouse and ANSI 108-Key keyboard R8. CPU speed shall be at least 1G Hz R9. The operating system shall be at least Windows 95.

Exercise

5

Where are we?

Next class – Validation