Two errors have appeared in my dissertation. First, in the symbolic statement of Theorem (14.1), “r i ≁∧” should be “r i ≁∨.” Second, as J. C. C. McKinsey points out in his review, Theorem (10.8) is not correct. The error in the proof enters in the last application of Theorem (10.7), for which the hypothesis would be needed. The construction given at the bottom of page 35 is valid, however.

To state the correct theorem to replace Theorem (10.8), adopt the notation sylc (p) for any one of the mutually congruent polynomials resulting from the adjunction to p of all σ-terms informally included in p which are obtainable by eliminating c from pairs of terms of p.Then:

Theorem. .