Erratum to J. M. Font, The simplest protoalgebraic logic

In [1], the statements of Non-Proposition 2.4 (on page 438) and of Propositions 2.5 and 2.6 (on page 439) have been published in incomplete form. The complete statements read as follows: Non-Proposition 2.4 We have I β if and only if β satisfies one of the following conditions: (a) β is a theorem. (b) β ∈ . (c) There is a finite, non-empty sequence α of formulas such that α → β ∈ and each αi satisfies one of the conditions (a), (b) or (c).