Chapter 8: Drawing a Map: Five Diagrams

Let us summarize some of the results of the previous chapters. In all of the diagrams below, no other implications than the ones shown (or implied by transitivity) hold. Readers may find it useful to go through the following diagrams and justify the implications and nonimplications, using results given above. Expanded versions of some of these diagrams can be found in Hirschfeldt and Jockusch [85]. These diagrams were generated by hand, but there is a tool available for automating the drawing of such diagrams, known as “The Reverse Mathematics Zoo”. At the time of writing, it is maintained by Damir Dzhafarov at rmzoo.uconn.edu…