from prior art(different situation exists where the solution is obvious from prior art which contains the same solution for a similar problem. Alexander Demidov)
prior art(Prior art (also known as state of the art, which also has other meanings, or background art), in most systems of patent law, constitutes all information that has been made available to the public in any form before a given date that might be relevant to a patent's claims of originality. If an invention has been described in the prior art, a patent on that invention is not valid. – WAD Alexander Demidov)