Jakob Taankvist

In a series of contributions Olderog et al. have formulated and verified safety controllers for a number of lane-maneuvers on multilane roads. Their work is characterized by great clarity and elegance partly due to the introduction of a special-purpose Multi-Lane Spatial Logic. In this paper, we want to illustrate the potential of current modelchecking technology for automatic synthesis of optimal yet safe (collisionfree) controllers. We demonstrate this potential on an Adaptive Cruise Control… Vis mere

In a series of contributions Olderog et al. have formulated and verified safety controllers for a number of lane-maneuvers on multilane roads. Their work is characterized by great clarity and elegance partly due to the introduction of a special-purpose Multi-Lane Spatial Logic. In this paper, we want to illustrate the potential of current modelchecking technology for automatic synthesis of optimal yet safe (collisionfree) controllers. We demonstrate this potential on an Adaptive Cruise Control problem, being a small part of the overall safety problem considered by Olderog.
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Uppaal Stratego is a novel tool which facilitates generation, optimization, comparison as well as consequence and performance exploration of strategies for stochastic priced timed games in a user-friendly manner. The tool allows for efficient and flexible “strategy-space” exploration before adaptation in a final implementation by maintaining strategies as first class objects in the model-checking query language. The paper describes the strategies and their properties, construction and… Vis mere

Uppaal Stratego is a novel tool which facilitates generation, optimization, comparison as well as consequence and performance exploration of strategies for stochastic priced timed games in a user-friendly manner. The tool allows for efficient and flexible “strategy-space” exploration before adaptation in a final implementation by maintaining strategies as first class objects in the model-checking query language. The paper describes the strategies and their properties, construction and transformation algorithms and a typical tool usage scenario. Vis mindre

(Priced) timed games are two-player quantitative games involving an environment assumed to be completely antogonistic. Classical analysis consists in the synthesis of strategies ensuring safety, time-bounded or cost-bounded reachability objectives. Assuming a randomized environment, the (priced) timed game essentially defines an infinite-state Markov (reward) decision proces. In this setting the objective is classically to find a strategy that will minimize the expected reachability cost, but… Vis mere

(Priced) timed games are two-player quantitative games involving an environment assumed to be completely antogonistic. Classical analysis consists in the synthesis of strategies ensuring safety, time-bounded or cost-bounded reachability objectives. Assuming a randomized environment, the (priced) timed game essentially defines an infinite-state Markov (reward) decision proces. In this setting the objective is classically to find a strategy that will minimize the expected reachability cost, but with no guarantees on worst-case behaviour. In this paper, we provide efficient methods for computing reachability strategies that will both ensure worst case time-bounds as well as provide (near-) minimal expected cost. Our method extends the synthesis algorithms of the synthesis tool Uppaal-Tiga with suitable adapted reinforcement learning techniques, that exhibits several orders of magnitude improvements w.r.t. previously known automated methods. Vis mindre

Timed analysis of real-time systems can be performed using continuous (symbolic) or discrete (explicit) techniques. The explicit state-space exploration can be considerably faster for models with moderately small constants, however, at the expense of high memory consumption. In the setting of timed-arc Petri nets, we explore new data structures for lowering the used memory: PTries for efficient storing of configurations and time darts for semi-symbolic description of the state-space. Both… Vis mere

Timed analysis of real-time systems can be performed using continuous (symbolic) or discrete (explicit) techniques. The explicit state-space exploration can be considerably faster for models with moderately small constants, however, at the expense of high memory consumption. In the setting of timed-arc Petri nets, we explore new data structures for lowering the used memory: PTries for efficient storing of configurations and time darts for semi-symbolic description of the state-space. Both methods are implemented as a part of the tool TAPAAL and the experiments document at least one order of magnitude of memory savings while preserving comparable verification times. Vis mindre

Verification of closed timed models by explicit state-space exploration methods is an alternative to the wide-spread symbolic techniques based on difference bound matrices (DBMs). A few experiments found in the literature confirm that for the reachability analysis of timed automata explicit techniques can compete with DBM-based algorithms, at least for situations where the constants used in the models are relatively small. To the best of our knowledge, the explicit methods have not yet been… Vis mere

Verification of closed timed models by explicit state-space exploration methods is an alternative to the wide-spread symbolic techniques based on difference bound matrices (DBMs). A few experiments found in the literature confirm that for the reachability analysis of timed automata explicit techniques can compete with DBM-based algorithms, at least for situations where the constants used in the models are relatively small. To the best of our knowledge, the explicit methods have not yet been employed in the verification of liveness properties in Petri net models extended with time. We present an algorithm for liveness analysis of closed Timed-Arc Petri Nets (TAPN) extended with weights, transport arcs, inhibitor arcs and age invariants and prove its correctness. The algorithm computes optimized maximum constants for each place in the net that bound the size of the reachable state-space. We document the efficiency of the algorithm by experiments comparing its performance with the state-of-the-art model checker UPPAAL. Vis mindre