In a number of chemistry decisions the problem and solution approach – based on landmark decisions T 1/80 (OJ 1981, 206), T 24/81 (OJ 1983, 133) and T 248/85 (OJ 1986, 261) – involves the following steps:

a) establishing the closest prior art;

b) defining the problem in the light of that prior art;

c) identifying the solution;

It would not be obvious to a skilled person to combine an isolated, very old document (i.e. 50 year old document), which had not given rise to a trend in the art and whose teaching ran counter to the present trend, with the document reflecting the closest state of the art (T 261/87, T 366/89, T 404/90).