Minimum observability of probabilistic Boolean networks
Jiayi Xu, Shihua Fu, Liyuan Xia, Jianjun Wang
TL;DR
This work tackles the minimum observability problem for probabilistic Boolean networks by formulating a STP-based algebraic representation and transforming observability into a robust set reachability issue on an augmented system. It then identifies minimal H-distinguishable state sets that must be separated and derives necessary and sufficient conditions to add the least number of measurements to achieve observability, selecting among feasible sensor configurations. A constructive algorithm is provided to compute the smallest sensor count via truth matrices and reachability analysis, and the approach is illustrated on a four-node apoptosis PBN. The results extend observability analysis to stochastic logical networks, offering practical observer-design options with reduced sensing costs and broad applicability to deterministic BNs as well. The methodology advances the theoretical and computational toolkit for monitoring and controlling gene regulatory-like networks under uncertainty.
Abstract
This paper studies the minimum observability of probabilistic Boolean networks (PBNs), the main objective of which is to add the fewest measurements to make an unobservable PBN become observable. First of all, the algebraic form of a PBN is established with the help of semi-tensor product (STP) of matrices. By combining the algebraic forms of two identical PBNs into a parallel system, a method to search the states that need to be H-distinguishable is proposed based on the robust set reachability technique. Secondly, a necessary and sufficient condition is given to find the minimum measurements such that a given set can be H-distinguishable. Moreover, by comparing the numbers of measurements for all the feasible H-distinguishable state sets, the least measurements that make the system observable are gained. Finally, an example is given to verify the validity of the obtained results.
