DEWS Colloquia

The Center of Excellence for Research DEWS is organizing a series of seminars.

Next seminar

Seminar #4:

Speaker: Dr. Catia Trubiani (Gran Sasso Science Institute, L’Aquila - Italy)

Title: Cyber Physical Systems: a software quality perspective on uncertainties

Abstract: Cyber-physical systems are exposed to multiple uncertainties due to mixing software and hardware components that operate in complex and changing environments. Uncertainty can be critical for software quality, especially in the presence of highly dynamic changes, for instance when alterations in the physical space affect the capability of a swarm of robots to complete a task on time. Incorporating uncertainty as a first-class concept in the software development process to identify quality issues is still challenging. This talk presents two ways of handling uncertainty: (i) performance models capturing how different architectural patterns affect the performance characteristics of the evolving physical space; (ii) uncertainty-aware testing strategies to drive the test case generation process. A goal of this research is to provide quantitative evaluation that supports system stakeholders in the identification of software quality issues.

Bio: Catia Trubiani is Assistant Professor at the Gran Sasso Science Institute (GSSI), Italy. Previously she collaborated with various international research institutes like the Karlsruhe Institute of Technology in Germany, and the Imperial College of London in UK. She is principal investigator of the GSSI unit for the MUR-PRIN project SEDUCE (Young Line action) and for the MUR-FISR project MVM-Adapt. In 2021 she received the Exceptional Reviewer Award for the International Conference on Software Architecture (ICSA), and the 10-year most influential paper for the International Conference on Performance Engineering (ICPE). More information is available here: http://cs.gssi.it/catia.trubiani

When: Monday November 22^nd 2021 from 15.00 to 16.00

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Seminar #3:

Speaker: Prof. Romain Postoyan (CNRS, CRAN, Université de Lorraine - France)

Title: Dynamical systems controlled by value iteration: stability, near-optimality and stopping criterion

Abstract: Value iteration (VI) is a ubiquitous algorithm for optimal control, planning, and reinforcement learning schemes. Under the right assumptions, VI is a vital tool to generate inputs with optimal properties for general nonlinear systems and cost functions. However, several important questions remain largely unexplored in the literature in particular: what can we say about the stability of systems whose inputs are obtained by VI? and what about their robustness properties? These properties are fundamental in numerous safety-critical control applications, it is thus of primary importance to make sure that the use of VI to construct the control inputs is done in such a way that robust stability of the closed-loop system is ensured. In this talk, we will provide answer to these questions for the case where the plant dynamics is known, deterministic nonlinear and in discrete-time. We will then see how stability can be exploited to significantly improve existing near-optimality bounds of the literature, i.e., the mismatch between the value function given by VI at each step and the targeted optimal value function. We will also provide some first elements on when to rigorously stop the algorithm and how to implement it.

When: Wednesday July 14th 2021 from 11.00 to 12.00

Where: Webex (Video link)

Seminar #2:

Speaker: Prof. Pasquale Palumbo (University of Milano-Bicocca, Italy)

Title: A mathematical model of the G1/S transition for the budding yeast

Abstract: In budding yeast, overcoming of a critical size to enter S phase and the mitosis/mating switch—two central cell fate events—take place in the G1 phase of the cell cycle. Here we present a mathematical model of the basic molecular mechanism controlling the G1/S transition, whose major regulatory feature is multisite phosphorylation of nuclear Whi5. Cln3–Cdk1, whose nuclear amount is proportional to cell size, and then Cln1,2–Cdk1, randomly phosphorylate both decoy and functional Whi5 sites. Full phosphorylation of functional sites releases Whi5 inhibitory activity, activating G1/S transcription. Simulation analysis shows that this mechanism ensures coherent release of Whi5 inhibitory action and accounts for many experimentally observed properties of mitotically growing or conjugating G1 cells. Cell cycle progression and transcriptional analyses of a Whi5 phosphomimetic mutant verify the model prediction that coherent transcription of the G1/S regulon and ensuing G1/S transition requires full phosphorylation of Whi5 functional sites

When: Monday June 28th 2021 from 14.30 to 15.30

Where: Webex

Seminar #1:

Speaker: Dr. Mirco Giacobbe (University of Oxford, UK)

Title: Neuro-symbolic Liveness Verification

Abstract: Liveness verification answers the question of whether a system always responds with desirable behavior or, dually, never gets stuck without responding at all. For dynamical systems, this relates to the stability question; for computer programs, it relates to the halting problem. I will talk about a novel method for constructing liveness proofs by learning witnesses (Lyapunov and ranking functions) from data using neural networks combined with symbolic reasoning. I will talk about how we apply this neuro-symbolic approach to the stability analysis of dynamical systems, to the termination analysis of Java programs, and to the almost-sure termination analysis of probabilistic programs.

When: Friday June 11th 2021 from 14.30 to 15.30

Where: Webex

Center of Excellence DEWS