This classic in the field is a compact introduction to some of the basic topics of mathematical logic. Major changes in this edition include a new section on semantic trees; an expanded chapter on Axiomatic Set Theory; and full coverage of effective computability, where Turing computability is now the central notion and diagrams (flow-charts) are used to construct Turing machines. Recursion theory is covered in more detail, including the s-m-n theorem, the recursion theorem and Rice's Theorem. New sections on register machines and random access machines will be of special interest to computer science students. The proofs of the incompleteness theorems are now based on the Diagonalization Lemma and the text also covers Lob's Theorem and its connections with Godel's Second Theorem. This edition contains many new examples and the notation has been updated throughout. This book should be of interest to introductory courses for students of mathematics, philosophy, computer science and electrical engineering.