Sets and Relations Mappings and Operations Algebras and Relational Systems Partially Ordered Sets Structure of Mappings and Equivalence Relations Ideals and Semilattices SUBALGEBRAS AND HOMOMORPHISMS Polynomial Symbols and Polynomial Algebras Structure of Subalgebras Structure of Congruence Relations The Homomorphism Theorem and Some Isomorphism Theorems Homomorphisms PARTIAL ALGEBRAS Polynomial Symbols over a Partial Algebra Extension of Congruence Relations Subalgebras and Homomorphisms of Partial Algebras The Characterization Theorem of Congruence Lattices: Preliminary Considerations The Characterization Theorem of Congruence Lattices CONSTRUCTIONS OF ALGEBRAS Direct Products Subdirect Products of Algebras Direct and Inverse Limits of Algebras Products Associated with the Direct Product Operators on Classes of Algebras FREE ALGEBRAS Definition and Basic Properties Construction of Free Algebras Identities and Free Algebras Equational Completeness and Identities of Finite Algebras Free Algebras Generated by Partial Algebras Free Products of Algebras Word Problem INDEPENDENCE Independence and Bases Independence in Special Classes of Algebras Some Invariants of Finite Algebras The System of Independent Sets of an Algebra . Generalizations of the Notion of Independence ELEMENTS OF MODEL THEORY Structures and the First Order Logic Satisfiability and the Case of Boolean Set Algebras Elementary Equivalence and Elementary Extensions Prime Products Prime Powers Two Algebraic Characterizations of Elementary Equivalence Elementary and Axiomatic Classes ELEMENTARY PROPERTIES OF ALGEBRAIC CONSTRUCTIONS Extensions and Substructures Generalized Atomic Sets of Formulas Chain Unions and Homomorphisms Direct Products Direct Products (Continued) Subdirect Products FREE S-STRUCTURES S-Inverses and Substructures S-Homomorphisms and Slender 2-Substructures Free Structures and the Uniqueness Theorem On the Family of Free Structures On the Existence of Free X-Structures Strong Free S-Structures and the Inverse Preserving Property