A. Ad­denda

This ap­pen­dix de­scribes a num­ber of ad­di­tional top­ics. They did not seem im­por­tant enough to war­rant in­clud­ing them in the main text. An ad­di­tion is al­ways a dis­trac­tion; at the min­i­mum you have to worry about whether you need to worry about it. How­ever, many of the top­ics be­low are cov­ered in well-known other texts. Ob­vi­ously many other au­thors dis­agree about their im­por­tance. If they turn out to be right, you can find it here.