This is a textbook in universal algebra for students of the Novosibirsk State Technical University. It consists of three chapters and 13 sections. The last chapter presents new facts on conditional term calculus recently obtained by A. G. Pinus. The contents are as follows.
Chapter 1. Basic notions of universal algebra: §1. Universal algebras, models, algebraic systems. Equivalence relation. §2. Subalgebras and representation theorems for groups, semigroups, Boolean algebras, and distributive lattices. §3. Algebraic lattices. §4. Homomorphisms, congruences, and factor-algebras. §5. Direct and subdirect products, ultraproducts. Operators on classes of algebras.
Chapter 2. Varieties and free algebras: §6. Free algebras in varieties. Absolutely free algebras. §7. Identities and equational classes. §8. Identities calculus. §9. Congruence-permutational, congruence-modular, congruence-distributive varieties. Discriminant varieties. §10. Rational equivalence of varieties.
Chapter 3. Conditional terms and varieties: §11. Conditional terms and conditionally termal functions. §12. Conditional equalities and conditional varieties. §13. Conditionally rational equivalence of conditional varieties and algebras.