In chemical kinetics, the elementary reactions are represented by the stoichiometric equations ∑ ∑ i α α r i A i ⟶ ⟶ ∑ ∑ j β β r j A j ( r = 1 , … … , m ) , where A i are the components and α α r i , β β r j ≥ ≥ 0 are the stoichiometric coefficients. Here, the reverse reactions with positive constants are included in the list separately. We need this separation of direct and reverse reactions to apply later the general formalism to the systems with some irreversible reactions. The system of stoichiometric equations of elementary reactions is the reaction mechanism.