Art. 56 EPC does not require that the problem to be solved should be novel in itself. The fact that the underlying problem of the patent have already been solved by the prior art does not necessarily require redefinition of the problem for the assessment of inventive step, if the subject-matter of the patent represents an alternative solution to this problem. (T 92/92, with reference to T 495/91; see also T 780/94, T 1074/93, T 323/03, T 824/05).
According to T 588/93, for an inventive step to be present, it was not necessary to show improvement – substantial or gradual – over the prior art. Thus an earlier solution to a given technical problem did not preclude later attempts to solve the same problem in another, non-obvious way (T 1791/08).