Takumi Akazaki

Learn More
Building on the work by Fainekos and Pappas and the one by Donzé and Maler, we introduce AvSTL, an extension of metric interval temporal logic by averaged temporal operators. Its expressivity in capturing both space and time robustness helps solving falsification problems (searching for a critical path in hybrid system models); it does so by communicating a(More)
The timed pattern matching problem is formulated by Ulus et al. and has been actively studied since, with its evident application in monitoring realtime systems. The problem takes as input a timed word/signal and a timed pattern (specified either by a timed regular expression or by a timed automaton); and it returns the set of those intervals for which the(More)
Inspired by a concrete industry problem we consider the input synthesis problem for hybrid systems: given a hybrid system that is subject to input from outside (also called disturbance or noise), find an input sequence that steers the system to the desired postcondition. In this paper we focus on sampled data systems—systems in which a digital controller(More)
Falsification is drawing attention in quality assurance of heterogeneous systems whose complexities are beyond most verification techniques’ scalability. In this paper we introduce the idea of causality aid in falsification: by providing a falsification solver—that relies on stochastic optimization of a certain cost function—with suitable causal information(More)
  • 1