This problem is derived from one of the failure diagrams of the One Day One Problem for Singapore's National Day.
However, unlike that problem, the White corner is dead in this problem.
The strongest resistance is for White to attempt to live by ko, as in the solution for RTG Problem 51.
However, can connect. This is really an under the stones problem.
The last hurdle in this problem is for Black to correctly respond to . As it happens, works because the chain of four White stones is short of liberties. Anything other than fails to kill unconditionally.