Symbolic Parity Game Solvers that Yield Winning Strategies

Parity games play an important role for LTL synthesis as evidenced by recent breakthroughs on LTL synthesis, which rely in part on parity game solving. Yet state space explosion remains a major issue if we want to scale to larger systems or specifications. In order to combat this problem, we need to investigate symbolic methods such as BDDs, which have been successful in the past to tackle exponentially large systems. It is therefore essential to have symbolic parity game solving algorithms, operating using BDDs, that are fast and that can produce the winning strategies used to synthesize the controller in LTL synthesis. Current symbolic parity game solving algorithms do not yield winning strategies. We now propose two symbolic algorithms that yield winning strategies, based on two recently proposed fixpoint algorithms. We implement the algorithms and empirically evaluate them using benchmarks obtained from SYNTCOMP 2020. Our conclusion is that the algorithms are competitive with or faster than an earlier symbolic implementation of Zielonka's recursive algorithm, while also providing the winning strategies.Comment: In Proceedings GandALF 2020, arXiv:2009.0936

The Fragmentation-Coherence Paradox in Twente

In this chapter, we will concentrate on the Dutch water authority of Vechtstromen, more specifically the region of Twente part of Vechtstromen. The Twente region has some 135,000 ha and about 630,000 inhabitants. Though most of the Netherlands is flat and the highly artificial system of waterways often enables to let water in from outside each region, a substantial part of the Twente region does not have this option and is thus fully dependent on rainwater and groundwater. Apart from the wetland nature areas, especially the northeast of the region is for this reason relatively vulnerable for water scarcity and droughts

Discrimination of simplified vowel spectra

One of the most important, and delicate, tasks of human hearing is speech recognition. Speech sounds show very quick variations over time, both in their intensities and in their frequency spectra. The basis ofspeech recognition is the ability to classify these sounds and to track changes in them. Much research has been performed on speech perception. This research has produced many rivalling models for the mechanisms behind the ability to distinguish speech and speech-like sounds (Moore, 1989). However, the theory of hearing does not provide exact answers concerning the nature and precision of the mechanisms to detect differences between speech-like sounds. Of old, two groups of theories have existed next to each other, one based on the spectra, and one based on the waveforms of sounds. Zie: Summary