Core Concepts
Step Chemical Reaction Networks with only bimolecular void rules ((2,0) rules) can efficiently compute threshold formulas and circuits.
Abstract
The paper demonstrates how Step Chemical Reaction Networks (step CRNs) using a limited set of reaction rules, called void rules, can efficiently compute threshold formulas (TFs) and threshold circuits (TCs).
Key highlights:
Step CRNs with only (2,0) void rules (bimolecular rules that can only delete species) can simulate TFs using linear resources (O(G) species, O(D) steps, O(G) volume).
By modifying the volume to be exponential, step CRNs with (2,0) void rules can also simulate TCs with O(G) species, O(D) steps, and O(GFoutD) volume, where Fout is the maximum fan-out of the circuit.
The paper also proves an exponential lower bound on the required volume for simulating TCs in a step CRN with (2,0) rules under a restricted gate-wise simulation, showing the optimality of the construction.
The authors first introduce how bits and logic gates are represented in the step CRN model. They then provide a detailed construction for computing TFs and TCs, followed by the complexity analysis and lower bound proof.