In the ACP-620 Practice Exam Questions, why is the answer to question 01.2060 option F?

[Janet Charbonneau]

In question 01.2060, the question is "You need to write a JQL query that shows all issues, except if they are epics or have the label BETA". The correct answer shown is option F. However, it states in the explanation that "It finds issue that are not epics and either have no labels or a value other than BETA." The question does not ask you to show issue with no label, so how is this the correct answer?

[Nic Brough -Adaptavist- · Accepted solution]

Because humans are bad at negative logic.

When you ask a logical system "show me things that are not X", humans don't understand that a thing has to have an attribute to compare. 

Logically, "show me the containers in the 'fridge that do not have curry in them" will only show me the containers that have something in them.  Imagine that the logic is comparing the contents with "curry".

Humans assume that empty containers also don't have curry in them, but logically, you can't actually do that test - an empty container has nothing to compare with curry.

So you need to be specific - "show me all the containers that do not have curry in them, including the ones that specifically have no content"

Same with labels - you need to ask "the label is not X, or there are no labels"

[Janet Charbonneau]

Thank you for that explanation! Now it makes sense. I wasn't understanding that it could not logically do a comparison if the labels field was empty. Your refrigerator example really helped me understand that logic!

[Brock Jolet]

Hello Janet,

Without looking at the practice exam directly, it sounds like they want you to think of it like this:

• Show all issues
• Subtract epics
• Subtract issues with the label BETA

If you do something like this...

type not in (Epic) AND labels not in (BETA)

...you will be inadvertently subtracting all issues without a label as well. 

Again my only context is your message, but it sounds like a misunderstanding of the request.