... contains a self-reducing point.Lemma 1.7 [5, Lemma 2.3]. If a Nielsen class C contains a self-reducing point (i.e., C isdefective), then any two points in this class are R-related, and thus|ind|( ... U,whichisdenotedby|ind|( f ,g;U).Definit ion 1.3. AcoincidenceclassC of a transverse pair ( f ,g) is called essential if|ind|( f ,g;C) = 0. In [5] Jezierski investigates whether a coincidence point x∈ Coin( ... con-tained in the same coincidence class of the pair (f , g)). Moreover, no two points of differentsubsets are Nielsen related.Lemma 3.6. Let x0, x1be coincidence points in the same coinc...