Secrets of understanding requirements

Word tricks

Negation and inversion

When requirements are hard to descern, you can get a better understanding by playing with words. Let's take a rather simple looking requirement:

• Fred must include a picture or a song in an email

Now, we can apply inverses at different points to change meanings. This allows us to ask questions:

• Fred MUST NOT include a picture or a song in an email
• Fred must include a picture AND a song in an email
• Fred must include a picture or a NON-song in an email
• Fred must include a NON-picture or a song in an email
• Fred must EXCLUDE a picture or a song in an email
• SOMEONE ELSE must include a picture or a song in an email
• Fred must include a picture or a song in a NON-email