Which texts do you recommend to study universal algebra and lattice theory?

Solution 1:

You should take a look at George Bergman's book "An Invitation to General Algebra and Universal Constructions". It's also free online, and it's a great introduction to the subject - it works through many concrete examples in Part I before getting to the abstract theory in Part II.

It doesn't contain much lattice theory, though.

Solution 2:

Imho, the best modern treatment of universal algebra is

Universal Algebra: Fundamentals and Selected Topics, by Cliff Bergman.

Algebras, Lattices, Varieties, by McKenzie, McNulty, Taylor is a classic and also excellent. Unfortunately, it is out of print, but most university libraries have a copy.

As mentioned by others, Burris and Sankapannavar is good (and free!). While it gives a very nice treatment of most of the basics, it was written a long time ago, and is starting to show its age. For example, there is little or no clone theory, and no mention of tame congruence theory (which was not invented until 1983). Fortunately, Cliff's new book has excellent coverage of both clones and tct.

Another list of resources for learning about universal algebra can be found here.

Unfortunately, none of the resources I've mentioned have very much to say about category theory and its relation to universal algebra and lattice theory (although, there is a very brief section in Algebras, Lattices, Varieties presenting categories from a universal algebra perspective).

Finally, since you are just getting your feet wet, I'll mention a couple more introductory references that I came across only recently (so don't know them well, but they look very interesting!) They are by well known/established authors:

Post-Modern Algebra, by Jonathan Smith and Anna Romanowska

Logical Foundations of Mathematics and Computational Complexity: A Gentle Introduction, by Pavel Pudlak

Solution 3:

I would like to mention the little known (but excellent) book by W. Wechler, Universal Algebra for Computer Scientists, Springer- Verlag, Berlin (1992). SBN: 978-3-642-76773-9 (Print) 978-3-642-76771-5 (Online).

It covers equational theories in great detail but also treats topics that are hardly found elsewhere, like multi-sorted algebras or ordered algebras.

Contents of the book.

1 Preliminaries

Basic Notions (Sets, Algebras Generation, Structural Induction, Algebraic Recursion and Deductive Systems)

Relations (Regular Operations, Equivalence Relations, Partial Orders, Terminating Relations, Well-quasi-Orders, Cofinality, Multiset Ordering and Polynomial Ordering).

Trees (Trees and Well-Founded Partially Ordered Sets, Labelled Trees, $\omega$-Complete Posets and Fixpoint Theorem, Free $\omega$-Completion).

2 Reductions

Word Problem (Confluence Method, Word Problem for Congruences) Reduction Systems (Abstract Reduction Systems, Term Rewriting Systems, Termination).

3 Universal Algebra

Basic Constructions (Subalgebras and Generation, Images and Presentation, Direct Products and Subdirect Decompositions, Reduced Products and Ultraproducts).

Equationally Defined Classes of Algebras (Equations, Free Algebras, Varieties, Equational Theories, Term Rewriting as an Algorithmic Tool for Equational Theories).

Implicationally Defined Classes of Algebras (Implications, Finitary Implications and Universal Horn Clauses, Sur-Reflections, Sur-Reflective Classes, Semivarieties and Quasivarieties).

Implicational Theories, Universal Horn Theories, Conditional Equational Theories and Conditional Term Rewriting.

4 Applications

Algebraic Specification of Abstract Data Types (Many-Sorted Algebras, Initial Semantics of Equational Specifications, Operational Semantics).

Algebraic Semantics of Recursive Program Schemes (Ordered Algebras, Strict Ordered Algebras, w-Complete Ordered Algebras, Recursive Program Schemes.

Appendix 1 : Sets and Classes.

Appendix 2 : Ordered Algebras as First-Order Structures.