The present invention is a method for automatic proving using many-sorted first-order logic. Embodiments of the invention apply a modified method of resolution of first-ordered logic. The method of resolution further comprises: processing at least one first sentence (P1) and at least one second sentence (Q1), wherein each of the at least one first sentence and the at least one second sentence contain literals (Pi, Qi). In addition, the method also restricts a unifying process in the method of resolution; determines the literals (Pi) of the at least one first sentence; negates the literals (Qi) of the at least one second sentence of the restricted unifying process; provides the determined literals (Pi′) and negated literals (Qi″) to the restricted unifying process; chooses a substitution list in the restricted unifying process with a predetermined type; and derives a resolvent sentence in response to the restricted unifying process and the chosen substitution list of predetermined type being unified.