Copyright (c) 1989-1996 by Gary T. Leavens. Permission is granted for you to make copies for educational and scholarly purposes, but not for direct commercial advantage, provided this notice appears on all copies. All other rights reserved. No guarantees or warranty for anything here. The order was first Hoare, then Dijkstra, then the Cohen homework, then the Hesselink homework. Cohen-chap2,3.notes.txt is not a homework, but a comment on a solution.