All exercises of this assignment are taken from
Due Date: Wednesday, December 5th, 2001.
3.5.15: The class of algebras considered is the one defined
in example 3.5.12 (All Sigma-1 algebras satisfying E).
The hint given in the last sentence of this
exercise ist wrong. Replace it by: Show that neither
A2 nor A3 is initial by showing that there are no
homomorphisms A2 -> A1 and A3 -> A1.
3.7.24 and 3.7.25: You should list all nontrivial critical pairs. Note
that a critical pair is only determined up to variable renaming.
Wed Feb 14 11:03:36 2018.