Brewster and Cluzel (Harvard) simulate 50 Boolean threshold networks (N=5000, power-law out-degree Ξ³=1.8, Kβ12.24) subjected to 10 shocks plus a control, and ask which m monitored nodes best identify the shock when initial states are noisy. Evolved (genetic-algorithm) panels of 8 reporters classify with accuracy 1.00 at Ξ΅=0 and 0.94 at Ξ΅=1, versus 0.47 and 0.35 for random panels and 1/11 chance .
The mechanistic core: sensitivity-ranked panels fail under noise because highly sensitive (promiscuous) nodes separate shocks mainly "by degree" and their readings scatter trial-to-trial, whereas dormant reporters respond to only a few shocks but flip completely and reproducibly. Nearly every evolved panel (47/50) contains at least one dormant member; across 400 members, 42.5% are dormant . Ablations support a "reserve" role: removing dormant members always costs accuracy (0.02 for one removal, 0.20 by three), and at full noise a dormant reporter is worth nearly as much as a promiscuous one .
The useful deliverable is a cheap rule: greedy maximization of the panel's low-tail (10th-percentile) Mahalanobis discriminabilityβthe "spring rule"βreaches 0.97/0.92/0.90 across noise levels, within 3β4 points of genetic search, without calling the classifier, and it independently rediscovers the promiscuousβdormant mix .
Blind spots. Everything is simulated in one deliberately minimal model class; the authors themselves flag graded responses, asynchronous updates, structured noise, and pathway-specific perturbations as unmodeled, and only single-time-snapshot readouts were tested. Empirical validation in bacterial drug response, neural recordings, or behaviorβpromised as "a natural next step"βis entirely absent, so the dormancy mechanism (pinned node states) may not transfer. Positive: code is released (github.com/davidb2/boolean-threshold-network), NP-completeness is proven for the worst case, snapshot-vs-trajectory split leakage was explicitly checked (0.960β0.945 at Ξ΅=0.5), and AI-assistance disclosure is transparent. What would weaken the central claim: mixed-in-dynamics experiments where a promiscuous-only or sensitivity-ranked panel matches mixed panels under realistic trial-to-trial variability.
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