While this reaction mechanism is supported by voluminous experimental kinetic and spectroscopic data as well as a variety of theoretical calculations, other models have been proposed, including monomer-active or monomer-dominant models. In these cases, however, it may be shown that the proposed model is neither consistent with, nor predictive of, the experimental findings, or that mathematical errors render the model invalid. For example, a model invoking a dimer catalytic species was proposed in which "the concentration of dimers is vanishingly small compared to that of the monomers," in contrast to the experimental spectroscopic findings that higher order (dimer/tetramer) species predominate. A "second- This assumption is clearly not valid in a model attempting to predict the evolution from low ee values to homochirality. The origin of this flawed assumption appears to be confusion between the mathematical operation (2•PR•PS), with PR and PS designated as the product monomers R and S, and the variable name chosen for the heterochiral dimer, which was termed PR•PS (where "•" signifies a chemical connection between the two enantiomers rather than mathematical multiplication). Thus, the rate equation was developed under the incorrect the kinetic model rate equation: