On the one hand, the problem whether the statement that p and q are relative primes is false can be suspended, because even if the statement that p and q are relative primes is false, it recognizes the fact that “both p and q are integers” since the concept of co-prime and the truth or falseness are both used for two integers. Then, if the original proposition that √2=p/q (p and q are not both integers) is true, it indicates that “p and q are not both integers”, which contradicts with the meaning “that both p and q are integers” contained in the conclusion “that the statement p and q are relative primes” is false. And this indicates the statement “that the original proposition is true if the counterproposition is false” is false. That is to say, the given counterproposition does not conform to the requirements of reductio ad absurdum, so reductio ad absurdum can’t be applied.