When is cumulative dose response monotonic? Analysis of incoherent feedforward motifs

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Main Authors: Wafi, Moh Kamalul, de Oliveira, Arthur C. B., Sontag, Eduardo D.
Format: Preprint
Published: 2026
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author Wafi, Moh Kamalul
de Oliveira, Arthur C. B.
Sontag, Eduardo D.
author_facet Wafi, Moh Kamalul
de Oliveira, Arthur C. B.
Sontag, Eduardo D.
contents We study the monotonicity of the cumulative dose response (cDR) for a class of incoherent feedforward motifs (IFFM) systems with linear intermediate dynamics and nonlinear output dynamics. While the instantaneous dose response (DR) may be nonmonotone with respect to the input, the cDR can still be monotone. To analyze this phenomenon, we derive an integral representation of the sensitivity of cDR with respect to the input and establish general sufficient conditions for both monotonicity and non-monotonicity. These results reduce the problem to verifying qualitative sign properties along system trajectories. We apply this framework to four canonical IFFM systems and obtain a complete characterization of their behavior. In particular, IFFM1 and IFFM3 exhibit monotone cDR despite potentially non-monotone DR, while IFFM2 is monotone already at the level of DR, which implies monotonicity of cDR. In contrast, IFFM4 violates these conditions, leading to a loss of monotonicity. Numerical simulations indicate that these properties persist beyond the structured initial conditions used in the analysis. Overall, our results provide a unified framework for understanding how network structure governs monotonicity in cumulative input-output responses.
format Preprint
id arxiv_https___arxiv_org_abs_2604_01573
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle When is cumulative dose response monotonic? Analysis of incoherent feedforward motifs
Wafi, Moh Kamalul
de Oliveira, Arthur C. B.
Sontag, Eduardo D.
Dynamical Systems
Systems and Control
We study the monotonicity of the cumulative dose response (cDR) for a class of incoherent feedforward motifs (IFFM) systems with linear intermediate dynamics and nonlinear output dynamics. While the instantaneous dose response (DR) may be nonmonotone with respect to the input, the cDR can still be monotone. To analyze this phenomenon, we derive an integral representation of the sensitivity of cDR with respect to the input and establish general sufficient conditions for both monotonicity and non-monotonicity. These results reduce the problem to verifying qualitative sign properties along system trajectories. We apply this framework to four canonical IFFM systems and obtain a complete characterization of their behavior. In particular, IFFM1 and IFFM3 exhibit monotone cDR despite potentially non-monotone DR, while IFFM2 is monotone already at the level of DR, which implies monotonicity of cDR. In contrast, IFFM4 violates these conditions, leading to a loss of monotonicity. Numerical simulations indicate that these properties persist beyond the structured initial conditions used in the analysis. Overall, our results provide a unified framework for understanding how network structure governs monotonicity in cumulative input-output responses.
title When is cumulative dose response monotonic? Analysis of incoherent feedforward motifs
topic Dynamical Systems
Systems and Control
url https://arxiv.org/abs/2604.01573