Basic Algebra I, 2nd Edition

499 pages | 1985 | PDF | 12,5 Mb


This book is by an expert algebraist who has rewritten his earlier introduction to algebra from the experience gained after 20 years as a Yale professor. It contains correct insightful proofs, carefully explained as clearly as possible without compromising their goal of reaching the bottom of each topic.


Other books say that one cannot square the circle with ruler and compass because it would require solving an algebraic equation with rational coefficients whose root is pi, and after all pi is a transcendental number. But Jacobson also proves that pi is a transcendental number, so as not to leave a logical gap. Naturally the burden on the student is somewhat higher than if he is merely told this fact without proof.

It is true that some other books include many more examples, and discuss them at extreme length, whereas Jacobson's book is less than 500 pages, hence cannot include as many words. But Jacobson's words are sometimes far better chosen, as he clearly understands the material at greater depth than other authors.

In his introduction to R modules, he discusses the most natural possible ring that acts on an abelian group: the ring of its endomorphisms. This is the true motivation behind the usefulness of R modules structures but is not even hinted at in most other books.

In his treatment of factorization in Noetherian domains, Jacobson carefully proves the existence of a single irredudible factor before proving existence of a complete factorization, thus avoiding perfectly a logical trap that some authors do not even notice.

In his discussion of the structure theory of finitely generated modules over a pid, he gives the concrete proof using diagonalization of matrices, that will actually be applied later to linear transformations, rather than some abstract existence proof that will be useless later, as many other authors do.

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