Incidentally although it is no part of the reason for declining the unblock request I will mention another point I am intrigued to know how a proof of non existence of something can possibly be constructive If I wish to prove that something exists then I may or may not do so in a way that shows how to construct it If however something does not exist then I can t possibly show how to construct it Either I have grossly misunderstood something or you don t actually know what it means to describe a proof as constructive