Question about the "Working Example" of the "Avalanche Consensus" documentation

Hey everyboy,
first of all - thanks a lot for having me here!

I read through the Avalanche Consensus chapter of the documentation today and struggle with understanding the Working Example section.
It would be really nice if you could help me with clearing up my misunderstandings!

In the middle of the example, the node learns about a transaction Y' which conflicts with transaction Y.
The example then states In this case, two of them say that they prefer Y' and two of them say that they do not prefer Y'
I do not understand why some of the validators would answer that they do not prefer Y’ in this case.

Figure 10 in the consensus whitepaper states that a validator will respond with a yes vote for a transaction T, if every ancestor T’ is preferred among competing transactions:

As far as I understand the example, the transaction Y’ has the ancestors W and V (and other accepted ancestors that were omitted from the example).
Both, W and V should be prefered because the do not have any competing transactions in the examnple as far as I see.

What is the reason for these validators to answer that they do not prefer Y’?

Thanks a lot in advance!

Additionally, I struggle with understanding the reason for the following sentence in the documentation. This will probably be clarified by the answer of the question above, but I still wanted to ask about it explicitly :slightly_smiling_face:

When a node is asked whether it prefers a given transaction, it replies yes if that transaction has the highest confidence of any transaction in the transaction’s conflict set

I am not able to find the strategy/pseudocode for this in the 5.2 Avalanche: Specification section of the whitepaper. Am I looking in the wrong place?

Thanks a lot for your time!