Hey Heather,
Thanks for the questions and welcome to the Forum! Proper inferences from these types of chains is hugely important, and not just for Games, so I'm glad you're addressing this early on!
The double-not arrow (
) in particular can cause problems for people, but hopefully I can help clear up some confusion.
I'd encourage you for now to think of that double-not as its two component relationships, instead of the single connection. That is, if we have something like this:
A
B
What that really tells us is two things:
A
NOT B ; and B
NOT A
In other words they can never be grouped/selected together, so the presence of one rules out the other. But when you treat the original diagram as two parts, it becomes much easier to see how chains can and can't be formed. Consider two new rules we could add to the diagram(s) above:
C
A
B
D
What inferences might result from the addition of those new ideas? Well, we can tie C to A as follows:
C
A
NOT B
So C
NOT B
Since the arrows all go in the same direction an inference is possible! But what about the B and D rule we added? To connect it, we need it to be linked via positive (without the "NOT") B:
D <--- B
NOT A [sorry, there's no right-to-left arrow icon]
But in looking at that the arrows go in different directions, so unfortunately we can't make any absolute inferences about D and A. That's something the test makers love to use as a trap, so you have to be really careful!
That's also why C
A
B allows for an inference (C
B), while A
B
D does not: the "B" in that connection isn't a positive B when moving from A (A gives you NOT B), but it is a positive B going to D...so you don't actually have the same variable there to make the connection in the first place!
By treating those types of relationships individually (rather than combining with
) you'll save yourself from making mistakes as you get more comfortable. And with time and practice you can begin to use double-nots more frequently once you're completely confident.
I hope that helps!
