Hi,
As some of you have probably noticed (thank you for the feedback!), there was a silly mistake in QM2 third week example solution number 4. We of course have sin^2(x) --> 0 instead of sin^2(x) --> 1 when x goes to 0.
I corrected the example solution. The arguments are now different, but we still have that perturbation theory doesn't work when omega = delta omega (this time it's due to unbounded probability rather than infinite probability).
Lauri