Version 0.4 released

Now that we are between academic terms, I have replaced v0.3 by v0.4. As always, previous versions are accessible on the Archive page. The changes are relatively minor, compared with previous version releases: Old Ch 2 (Sets and functions) has been split into two chapters in v0.4—Ch 2 (Sets) and Ch 3 (Functions)—with old §2.1 … Read more