Why Does the Diagram in Kleppner's Example 2.3 Seem Incorrect?

[Granger]

Hey.
I'm studying Kleppner's book and I have a few questions about the example 2.3. Astronauts' Tug-of-War.

It's said that "The negative sign means that aB is to the left", but in the diagram represents aB to the right... Why is this happening? Or are we talking about different situations?
In fact, aA and aB should have opposite directions, which doesn't fit with our diagram... Can someone clarify this, please?

 

[Doc Al]

Hey.
I'm studying Kleppner's book and I have a few questions about the example 2.3. Astronauts' Tug-of-War.

It's said that "The negative sign means that aB is to the left", but in the diagram represents aB to the right... Why is this happening? Or are we talking about different situations?
In fact, aA and aB should have opposite directions, which doesn't fit with our diagram... Can someone clarify this, please?

The diagram just shows the direction of positive acceleration, which is to the right. It defines the sign convention. When you calculate the actual acceleration of aB, it turns out to be negative since B accelerates to the left.