members yield unique reactions (Figure -3). Note that, because we allow for electrochemical reactions, charge is not necessarily balanced in these reactions. For a system of several thousand species, there can easily be hundreds of billions or even trillions of stoichiometrically valid reactions. Reaction filters are therefore employed to remove reactions that, despite being stoichiometrically valid, are chemically implausible or otherwise undesirable (Figure ). All reaction filters employed in this work are described in Methods and are discussed in more detail in the Supplementary Information. Finally, the reactions from each bucket that pass all filters are aggregated. The result of HiPRGen is a set of filtered species S f iltered and filtered reactions R f iltered , which constitute a CRN.