Résumé : We present a method for patching faulty conjectures in automatic theorem proving. The method is based on well-known folding/unfolding deduction rules. The conjectures we are interested in here are implicative formulas that are of the following form\,: $\forall \overline{ x}~\phi( \overline{ x})=\forall \overline{x} ~\exists \overline{Y} ~\Gamma(\overline{x},\overline{Y}) \leftarrow \Delta(\overline{x})$. A faulty conjecture is a statement $\forall \overline{ x}~\phi( \overline{ x})$, which is not provable in some given program ${\cal T}$, defining all the predicates occurring in $\phi$, i.e, ${\cal M(T)}\not \models \forall \overline{ x}~ \phi( \overline{ x})$, where ${\cal M(T)}$ means the least Herbrand model of ${\cal T}$, but it would be if enough conditions, say $P$, were assumed to hold, i.e., ${\cal M(T\cup P)}\models \forall \overline{ x}~ \phi( \overline{ x})\leftarrow P$, where ${\cal P}$ is the definition of $P$. The missing hypothesis $P$ is called a corrective predicate for $\phi$. To construct $P$, we use the abduction mechanism that is the process of hypothesis formation. In this paper, we use the logic based approach because it is suitable for the application of deductive rules.