The paper discusses three different kinds of syntactic ill-formedness: ellipsis, conjunctions, and actual syntactic errors. It is shown how a new grammatical formalism, based on a two-level repr_e sentation of the syntactic knowledge is used to cope with Ill-formed sentences. The basic control struc ture of the parser is briefly sketched; the paper shows that it can be applied without any substan tial change both to correct and to ill-formed sen tences. This is achieved by introducing a mechanism for the hypothesization of syntactic structures, which is largely independent of the rules defining the well-formedness. .
