I made two typos of my own: 'corect' should be 'correct' and 'Signmaster' (obviously an improvement on the original) should be 'Singmaster'. In general it is di

I made two typos of my own: 'corect' should be 'correct' and 'Signmaster' (obviously an improvement on the original) should be 'Singmaster'. In general it is difficult to write even one page of correct mathematics, and this is a preview. I don't know how well soliciting content will work, given the copyright.