Salamanca, España
Spanish irregular verbs have been described in the grammars and works of reference according to the nature of the vowel, consonant or mixed alternations. But the complexity in the conjugation of many verbs, which have alternations of different type in the different paradigms, and the mixture of morphological and phonological criteria in their classification, impedes the homogeneity of the groups in this kind of descriptions. In this paper, Spanish irregular verbs are classified by models of well defined morphonological alternations and by verb tenses: models of irregularity in the present, past and future paradigms, and models of irregularity in the gerunds. This division is necessary to classify homogeneous groups of verbs that share the same scheme of irregularity. Likewise, a second classification shows the different models of irregular conjugation derived from the combination of the aforementioned alternation models. Both groups complete the classification of the irregular Spanish verbs of morphonological character. These schemes or models of irregularity are very useful for learning paradigms, because they group verbs that share formal (phonological) and morphological features (schemes of irregular conjugation).