@inproceedings{6985, abstract = {In this paper, we introduce a novel method to interpret recurrent neural networks (RNNs), particularly long short-term memory networks (LSTMs) at the cellular level. We propose a systematic pipeline for interpreting individual hidden state dynamics within the network using response characterization methods. The ranked contribution of individual cells to the network's output is computed by analyzing a set of interpretable metrics of their decoupled step and sinusoidal responses. As a result, our method is able to uniquely identify neurons with insightful dynamics, quantify relationships between dynamical properties and test accuracy through ablation analysis, and interpret the impact of network capacity on a network's dynamical distribution. Finally, we demonstrate the generalizability and scalability of our method by evaluating a series of different benchmark sequential datasets.}, author = {Hasani, Ramin and Amini, Alexander and Lechner, Mathias and Naser, Felix and Grosu, Radu and Rus, Daniela}, booktitle = {Proceedings of the International Joint Conference on Neural Networks}, isbn = {9781728119854}, location = {Budapest, Hungary}, publisher = {IEEE}, title = {{Response characterization for auditing cell dynamics in long short-term memory networks}}, doi = {10.1109/ijcnn.2019.8851954}, year = {2019}, } @inbook{7453, abstract = {We illustrate the ingredients of the state-of-the-art of model-based approach for the formal design and verification of cyber-physical systems. To capture the interaction between a discrete controller and its continuously evolving environment, we use the formal models of timed and hybrid automata. We explain the steps of modeling and verification in the tools Uppaal and SpaceEx using a case study based on a dual-chamber implantable pacemaker monitoring a human heart. We show how to design a model as a composition of components, how to construct models at varying levels of detail, how to establish that one model is an abstraction of another, how to specify correctness requirements using temporal logic, and how to verify that a model satisfies a logical requirement.}, author = {Alur, Rajeev and Giacobbe, Mirco and Henzinger, Thomas A and Larsen, Kim G. and Mikučionis, Marius}, booktitle = {Computing and Software Science}, editor = {Steffen, Bernhard and Woeginger, Gerhard}, isbn = {9783319919072}, issn = {0302-9743}, pages = {452--477}, publisher = {Springer Nature}, title = {{Continuous-time models for system design and analysis}}, doi = {10.1007/978-3-319-91908-9_22}, volume = {10000}, year = {2019}, } @inproceedings{7576, abstract = {We present the results of a friendly competition for formal verification of continuous and hybrid systems with nonlinear continuous dynamics. The friendly competition took place as part of the workshop Applied Verification for Continuous and Hybrid Systems (ARCH) in 2019. In this year, 6 tools Ariadne, CORA, DynIbex, Flow*, Isabelle/HOL, and JuliaReach (in alphabetic order) participated. They are applied to solve reachability analysis problems on four benchmark problems, one of them with hybrid dynamics. We do not rank the tools based on the results, but show the current status and discover the potential advantages of different tools.}, author = {Immler, Fabian and Althoff, Matthias and Benet, Luis and Chapoutot, Alexandre and Chen, Xin and Forets, Marcelo and Geretti, Luca and Kochdumper, Niklas and Sanders, David P. and Schilling, Christian}, booktitle = {EPiC Series in Computing}, issn = {23987340}, location = {Montreal, Canada}, pages = {41--61}, publisher = {EasyChair Publications}, title = {{ARCH-COMP19 Category Report: Continuous and hybrid systems with nonlinear dynamics}}, doi = {10.29007/m75b}, volume = {61}, year = {2019}, } @inproceedings{8570, abstract = {This report presents the results of a friendly competition for formal verification of continuous and hybrid systems with linear continuous dynamics. The friendly competition took place as part of the workshop Applied Verification for Continuous and Hybrid Systems (ARCH) in 2019. In its third edition, seven tools have been applied to solve six different benchmark problems in the category for linear continuous dynamics (in alphabetical order): CORA, CORA/SX, HyDRA, Hylaa, JuliaReach, SpaceEx, and XSpeed. This report is a snapshot of the current landscape of tools and the types of benchmarks they are particularly suited for. Due to the diversity of problems, we are not ranking tools, yet the presented results provide one of the most complete assessments of tools for the safety verification of continuous and hybrid systems with linear continuous dynamics up to this date.}, author = {Althoff, Matthias and Bak, Stanley and Forets, Marcelo and Frehse, Goran and Kochdumper, Niklas and Ray, Rajarshi and Schilling, Christian and Schupp, Stefan}, booktitle = {EPiC Series in Computing}, issn = {23987340}, location = {Montreal, Canada}, pages = {14--40}, publisher = {EasyChair}, title = {{ARCH-COMP19 Category Report: Continuous and hybrid systems with linear continuous dynamics}}, doi = {10.29007/bj1w}, volume = {61}, year = {2019}, } @inproceedings{6884, abstract = {In two-player games on graphs, the players move a token through a graph to produce a finite or infinite path, which determines the qualitative winner or quantitative payoff of the game. We study bidding games in which the players bid for the right to move the token. Several bidding rules were studied previously. In Richman bidding, in each round, the players simultaneously submit bids, and the higher bidder moves the token and pays the other player. Poorman bidding is similar except that the winner of the bidding pays the "bank" rather than the other player. Taxman bidding spans the spectrum between Richman and poorman bidding. They are parameterized by a constant tau in [0,1]: portion tau of the winning bid is paid to the other player, and portion 1-tau to the bank. While finite-duration (reachability) taxman games have been studied before, we present, for the first time, results on infinite-duration taxman games. It was previously shown that both Richman and poorman infinite-duration games with qualitative objectives reduce to reachability games, and we show a similar result here. Our most interesting results concern quantitative taxman games, namely mean-payoff games, where poorman and Richman bidding differ significantly. A central quantity in these games is the ratio between the two players' initial budgets. While in poorman mean-payoff games, the optimal payoff of a player depends on the initial ratio, in Richman bidding, the payoff depends only on the structure of the game. In both games the optimal payoffs can be found using (different) probabilistic connections with random-turn games in which in each turn, instead of bidding, a coin is tossed to determine which player moves. While the value with Richman bidding equals the value of a random-turn game with an un-biased coin, with poorman bidding, the bias in the coin is the initial ratio of the budgets. We give a complete classification of mean-payoff taxman games that is based on a probabilistic connection: the value of a taxman bidding game with parameter tau and initial ratio r, equals the value of a random-turn game that uses a coin with bias F(tau, r) = (r+tau * (1-r))/(1+tau). Thus, we show that Richman bidding is the exception; namely, for every tau <1, the value of the game depends on the initial ratio. Our proof technique simplifies and unifies the previous proof techniques for both Richman and poorman bidding. }, author = {Avni, Guy and Henzinger, Thomas A and Zikelic, Dorde}, location = {Aachen, Germany}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Bidding mechanisms in graph games}}, doi = {10.4230/LIPICS.MFCS.2019.11}, volume = {138}, year = {2019}, }