Two equivalence relations between geometric figures were used&colon; congruence and similarity. Rogers described the concepts of "congruence" and "incongruence" as important ideas in his theory. The quotients by congruence subgroups are of significant interest. The congruence relation, modulo , partitions the set of integers into congruence classes. The definition of a congruence depends on the type of algebraic structure under consideration. Congruence and similarity are concepts that describe when two shapes have similar characteristics. A plane that satisfies Hilbert's Incidence, Betweeness and Congruence axioms is called a Hilbert plane. Thus the notion of congruence classes modulo "n" that are coprime to "n" is well-defined. These include empathy, unconditional positive regard, congruence, and attitude versus technique. Scriptural validity, to him, stems from its congruence with experiential truth and not vice versa. In particular, Zeller's congruence and the Doomsday algorithm make heavy use of modulo-7 arithmetic. AAA is sufficient for congruence on a given curvature of surface. This concept alludes to the significance of congruence among emotions, appraisal, and cognitions. Sikh ethics emphasize the congruence between spiritual development and everyday moral conduct. Most general-purpose factoring algorithms are based on the congruence of squares method.