Well , that 's  that 's one thing , but see the other thing is that , um , I mean it 's good to take the difficult case , but let 's  let 's consider what that means. What  what we 're saying is that one o one of the things that  I mean my interpretation of your  your s original suggestion is something like this , as motivation. When we train on data that is in one sense or another , similar to the testing data , then we get a win by having discriminant training.
Mm - hmm.
When we train on something that 's quite different , we have a potential to have some problems.
Mm - hmm.