>>C
>....
>> The losing cases come from when the car is behind door A. Here Monty has a choice, he can open door B or C. If he always opens door B he shifts ...
>
>Once again you are not using the lettering system used by
>Devlin where the letters are not applied until after the
>choices are made.

That is not true here is what Delvin said:

"Suppose the doors are labeled A, B, and C. Let's assume the contestant initially picks door A. The probability that the prize is behind door A is 1/3. That means that the probability it is behind one of the other two doors (B or C) is 2/3. Monty now opens one of the doors B and C to reveal that there is no prize there. Let's suppose he opens door C."

Delvin did not say that Monty picks one of the two remaining doors
and then labels that door C.

>Monty does indeed have a choice between
>two doors but the labels "B" and "C" are not applied until
>after the contestant choses door "A" and Monty next opens a
>door. Regardless of which door Monty opens that door is
>labeled "C" and the remaining door is labeled "B".

I agree that such a labeling system changes the problem
but that is not the spirit of the orginial question in which
three doors each have distinct identities given by A B and C
or if you prefer 1,2,3. People can judge for themselves what
they think Delvin really meant.