@proceedings{638,
editor = {Bogomolov, Sergiy and Martel, Matthieu and Prabhakar, Pavithra},
publisher = {Springer},
title = {{Numerical Software Verification}},
doi = {10.1007/978-3-319-54292-8},
volume = {10152},
year = {2017},
}
@inproceedings{549,
abstract = {Model checking is usually based on a comprehensive traversal of the state space. Causality-based model checking is a radically different approach that instead analyzes the cause-effect relationships in a program. We give an overview on a new class of model checking algorithms that capture the causal relationships in a special data structure called concurrent traces. Concurrent traces identify key events in an execution history and link them through their cause-effect relationships. The model checker builds a tableau of concurrent traces, where the case splits represent different causal explanations of a hypothetical error. Causality-based model checking has been implemented in the ARCTOR tool, and applied to previously intractable multi-threaded benchmarks.},
author = {Finkbeiner, Bernd and Kupriyanov, Andrey},
booktitle = {Electronic Proceedings in Theoretical Computer Science},
issn = {20752180},
location = {Uppsala, Sweden},
pages = {31 -- 38},
publisher = {Open Publishing Association},
title = {{Causality-based model checking}},
doi = {10.4204/EPTCS.259.3},
volume = {259},
year = {2017},
}
@article{467,
abstract = {Recently there has been a significant effort to handle quantitative properties in formal verification and synthesis. While weighted automata over finite and infinite words provide a natural and flexible framework to express quantitative properties, perhaps surprisingly, some basic system properties such as average response time cannot be expressed using weighted automata or in any other known decidable formalism. In this work, we introduce nested weighted automata as a natural extension of weighted automata, which makes it possible to express important quantitative properties such as average response time. In nested weighted automata, a master automaton spins off and collects results from weighted slave automata, each of which computes a quantity along a finite portion of an infinite word. Nested weighted automata can be viewed as the quantitative analogue of monitor automata, which are used in runtime verification. We establish an almost-complete decidability picture for the basic decision problems about nested weighted automata and illustrate their applicability in several domains. In particular, nested weighted automata can be used to decide average response time properties.},
author = {Chatterjee, Krishnendu and Henzinger, Thomas A and Otop, Jan},
issn = {15293785},
journal = {ACM Transactions on Computational Logic (TOCL)},
number = {4},
publisher = {ACM},
title = {{Nested weighted automata}},
doi = {10.1145/3152769},
volume = {18},
year = {2017},
}
@inproceedings{633,
abstract = {A Rapidly-exploring Random Tree (RRT) is an algorithm which can search a non-convex region of space by incrementally building a space-filling tree. The tree is constructed from random points drawn from system’s state space and is biased to grow towards large unexplored areas in the system. RRT can provide better coverage of a system’s possible behaviors compared with random simulations, but is more lightweight than full reachability analysis. In this paper, we explore some of the design decisions encountered while implementing a hybrid extension of the RRT algorithm, which have not been elaborated on before. In particular, we focus on handling non-determinism, which arises due to discrete transitions. We introduce the notion of important points to account for this phenomena. We showcase our ideas using heater and navigation benchmarks.},
author = {Bak, Stanley and Bogomolov, Sergiy and Henzinger, Thomas A and Kumar, Aviral},
editor = {Abate, Alessandro and Bodo, Sylvie},
isbn = {978-331963500-2},
location = {Heidelberg, Germany},
pages = {83 -- 89},
publisher = {Springer},
title = {{Challenges and tool implementation of hybrid rapidly exploring random trees}},
doi = {10.1007/978-3-319-63501-9_6},
volume = {10381},
year = {2017},
}
@inproceedings{950,
abstract = {Two-player games on graphs are widely studied in formal methods as they model the interaction between a system and its environment. The game is played by moving a token throughout a graph to produce an infinite path. There are several common modes to determine how the players move the token through the graph; e.g., in turn-based games the players alternate turns in moving the token. We study the bidding mode of moving the token, which, to the best of our knowledge, has never been studied in infinite-duration games. Both players have separate budgets, which sum up to $1$. In each turn, a bidding takes place. Both players submit bids simultaneously, and a bid is legal if it does not exceed the available budget. The winner of the bidding pays his bid to the other player and moves the token. For reachability objectives, repeated bidding games have been studied and are called Richman games. There, a central question is the existence and computation of threshold budgets; namely, a value t\in [0,1] such that if\PO's budget exceeds $t$, he can win the game, and if\PT's budget exceeds 1-t, he can win the game. We focus on parity games and mean-payoff games. We show the existence of threshold budgets in these games, and reduce the problem of finding them to Richman games. We also determine the strategy-complexity of an optimal strategy. Our most interesting result shows that memoryless strategies suffice for mean-payoff bidding games.
},
author = {Avni, Guy and Henzinger, Thomas A and Chonev, Ventsislav K},
issn = {1868-8969},
location = {Berlin, Germany},
publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik},
title = {{Infinite-duration bidding games}},
doi = {10.4230/LIPIcs.CONCUR.2017.21},
volume = {85},
year = {2017},
}
@inproceedings{962,
abstract = {We present a new algorithm for model counting of a class of string constraints. In addition to the classic operation of concatenation, our class includes some recursively defined operations such as Kleene closure, and replacement of substrings. Additionally, our class also includes length constraints on the string expressions, which means, by requiring reasoning about numbers, that we face a multi-sorted logic. In the end, our string constraints are motivated by their use in programming for web applications. Our algorithm comprises two novel features: the ability to use a technique of (1) partial derivatives for constraints that are already in a solved form, i.e. a form where its (string) satisfiability is clearly displayed, and (2) non-progression, where cyclic reasoning in the reduction process may be terminated (thus allowing for the algorithm to look elsewhere). Finally, we experimentally compare our model counter with two recent works on model counting of similar constraints, SMC [18] and ABC [5], to demonstrate its superior performance.},
author = {Trinh, Minh and Chu, Duc Hiep and Jaffar, Joxan},
editor = {Majumdar, Rupak and Kunčak, Viktor},
issn = {03029743},
location = {Heidelberg, Germany},
pages = {399 -- 418},
publisher = {Springer},
title = {{Model counting for recursively-defined strings}},
doi = {10.1007/978-3-319-63390-9_21},
volume = {10427},
year = {2017},
}
@inproceedings{711,
abstract = {Nested weighted automata (NWA) present a robust and convenient automata-theoretic formalism for quantitative specifications. Previous works have considered NWA that processed input words only in the forward direction. It is natural to allow the automata to process input words backwards as well, for example, to measure the maximal or average time between a response and the preceding request. We therefore introduce and study bidirectional NWA that can process input words in both directions. First, we show that bidirectional NWA can express interesting quantitative properties that are not expressible by forward-only NWA. Second, for the fundamental decision problems of emptiness and universality, we establish decidability and complexity results for the new framework which match the best-known results for the special case of forward-only NWA. Thus, for NWA, the increased expressiveness of bidirectionality is achieved at no additional computational complexity. This is in stark contrast to the unweighted case, where bidirectional finite automata are no more expressive but exponentially more succinct than their forward-only counterparts.},
author = {Chatterjee, Krishnendu and Henzinger, Thomas A and Otop, Jan},
issn = {18688969},
location = {Berlin, Germany},
publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik},
title = {{Bidirectional nested weighted automata}},
doi = {10.4230/LIPIcs.CONCUR.2017.5},
volume = {85},
year = {2017},
}
@inproceedings{963,
abstract = {Network games are widely used as a model for selfish resource-allocation problems. In the classical model, each player selects a path connecting her source and target vertex. The cost of traversing an edge depends on the number of players that traverse it. Thus, it abstracts the fact that different users may use a resource at different times and for different durations, which plays an important role in defining the costs of the users in reality. For example, when transmitting packets in a communication network, routing traffic in a road network, or processing a task in a production system, the traversal of the network involves an inherent delay, and so sharing and congestion of resources crucially depends on time. We study timed network games , which add a time component to network games. Each vertex v in the network is associated with a cost function, mapping the load on v to the price that a player pays for staying in v for one time unit with this load. In addition, each edge has a guard, describing time intervals in which the edge can be traversed, forcing the players to spend time on vertices. Unlike earlier work that add a time component to network games, the time in our model is continuous and cannot be discretized. In particular, players have uncountably many strategies, and a game may have uncountably many pure Nash equilibria. We study properties of timed network games with cost-sharing or congestion cost functions: their stability, equilibrium inefficiency, and complexity. In particular, we show that the answer to the question whether we can restrict attention to boundary strategies, namely ones in which edges are traversed only at the boundaries of guards, is mixed. },
author = {Avni, Guy and Guha, Shibashis and Kupferman, Orna},
issn = {18688969},
location = {Aalborg, Denmark},
publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik},
title = {{Timed network games with clocks}},
doi = {10.4230/LIPIcs.MFCS.2017.37},
volume = {83},
year = {2017},
}
@article{743,
abstract = {This special issue of the Journal on Formal Methods in System Design is dedicated to Prof. Helmut Veith, who unexpectedly passed away in March 2016. Helmut Veith was a brilliant researcher, inspiring collaborator, passionate mentor, generous friend, and valued member of the formal methods community. Helmut was not only known for his numerous and influential contributions in the field of automated verification (most prominently his work on Counterexample-Guided Abstraction Refinement [1,2]), but also for his untiring and passionate efforts for the logic community: he co-organized the Vienna Summer of Logic (an event comprising twelve conferences and numerous workshops which attracted thousands of researchers from all over the world), he initiated the Vienna Center for Logic and Algorithms (which promotes international collaboration on logic and algorithms and organizes outreach events such as the LogicLounge), and he coordinated the Doctoral Program on Logical Methods in Computer Science at TU Wien (currently educating more than 40 doctoral students) and a National Research Network on Rigorous Systems Engineering (uniting fifteen researchers in Austria to address the challenge of building reliable and safe computer
systems). With his enthusiasm and commitment, Helmut completely reshaped the Austrian research landscape in the field of logic and verification in his few years as a full professor at TU Wien.},
author = {Gottlob, Georg and Henzinger, Thomas A and Weißenbacher, Georg},
journal = {Formal Methods in System Design},
number = {2},
pages = {267 -- 269},
publisher = {Springer},
title = {{Preface of the special issue in memoriam Helmut Veith}},
doi = {10.1007/s10703-017-0307-6},
volume = {51},
year = {2017},
}
@article{1196,
abstract = {We define the . model-measuring problem: given a model . M and specification . ϕ, what is the maximal distance . ρ such that all models . M' within distance . ρ from . M satisfy (or violate) . ϕ. The model-measuring problem presupposes a distance function on models. We concentrate on . automatic distance functions, which are defined by weighted automata. The model-measuring problem subsumes several generalizations of the classical model-checking problem, in particular, quantitative model-checking problems that measure the degree of satisfaction of a specification; robustness problems that measure how much a model can be perturbed without violating the specification; and parameter synthesis for hybrid systems. We show that for automatic distance functions, and (a) . ω-regular linear-time, (b) . ω-regular branching-time, and (c) hybrid specifications, the model-measuring problem can be solved.We use automata-theoretic model-checking methods for model measuring, replacing the emptiness question for word, tree, and hybrid automata by the . optimal-value question for the weighted versions of these automata. For automata over words and trees, we consider weighted automata that accumulate weights by maximizing, summing, discounting, and limit averaging. For hybrid automata, we consider monotonic (parametric) hybrid automata, a hybrid counterpart of (discrete) weighted automata.We give several examples of using the model-measuring problem to compute various notions of robustness and quantitative satisfaction for temporal specifications. Further, we propose the modeling framework for model measuring to ease the specification and reduce the likelihood of errors in modeling.Finally, we present a variant of the model-measuring problem, called the . model-repair problem. The model-repair problem applies to models that do not satisfy the specification; it can be used to derive restrictions, under which the model satisfies the specification, i.e., to repair the model.},
author = {Henzinger, Thomas A and Otop, Jan},
journal = {Nonlinear Analysis: Hybrid Systems},
pages = {166 -- 190},
publisher = {Elsevier},
title = {{Model measuring for discrete and hybrid systems}},
doi = {10.1016/j.nahs.2016.09.001},
volume = {23},
year = {2017},
}