Reaction complex
= Reaction complex
{title2=$y=\sum_i y_iA_i$}
A formal combination of <chemical species> appearing on one side of a <chemical reaction>. The coefficients $y_i$ are nonnegative integers. A <chemical reaction network> can be viewed as a directed <graph> whose <vertices> are reaction complexes and whose <edges> are <chemical reactions>. The empty complex represents external production or removal.