Our ripple-carry CRN has four input species per adder representing the two inputs, and two output species representing the output. In Fig. 21 we show that the adder exhibits correct behaviour by producing the desired output species for a specific input, where each sum is calculated only in the next stage in the pipeline. If we view each C-element and adder as one stage in the pipeline, labelled A, B and C, then we can view the output species of each adder as a bridge to the next adder. The six output species, representing the carry-bit output, are denoted by \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A_{abridgeOneOut}, B_{bbridgeOneOut}, C_{cbridgeOneOut}$$\end{document}AabridgeOneOut,BbbridgeOneOut,CcbridgeOneOut and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A_{abridgeZeroOut}, B_{bbridgeZeroOut}, C_{cbridgeZeroOut}$$\end{document}AabridgeZeroOut,BbbridgeZeroOut,CcbridgeZeroOut. In order to show correct operation the output of the adders (represented in this case by 10 molecules) should be interleaved with the control species of the C-pipeline (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A_{hi},B_{hi},C_{hi}$$\end{document}Ahi,Bhi,Chi), allowing time for the carry species to catalyse with the input of the following adder.Fig. 21Deterministic simulation of the ripple-carry adder circuit responding to various inputs. We plot the output species from each section of the pipeline used to coordinate the output from each adder. The carry-bit output from each adder is represented by \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A_{abridgeOneOut}, B_{bbridgeOneOut}$$\end{document}AabridgeOneOut,BbbridgeOneOut and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$C_{cbridgeOneOut}$$\end{document}CcbridgeOneOut. The output of the C-element (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A_{hi},B_{hi},C_{hi}$$\end{document}Ahi,Bhi,Chi) arrives strictly before the output from the adder. The logical input for a is 1 and 0 for the first adder, 1 and 0 for the second adder, and 1 and 0 for the third adder. In b we show the computation on different inputs, namely 1 and 0 for the first adder, 0 and 0 for the second adder, and 1 and 0 for the third adder. The crossover in the concentrations of output species of the C-element and the logical output of 1 (resulting from inputs 0, 1 and carry of 1) in the third adder (plots \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$C_{hi}$$\end{document}Chi and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$C_{csOneOut}$$\end{document}CcsOneOut) indicates faster convergence but does not affect the results in further stages of the pipeline