The Dynamic Complexity of the Reachability Problem on Graphs

2013 ◽  
pp. 45-45
Author(s):  
Thomas Schwentick
Keyword(s):  
Reachability Problem ◽  
Dynamic Complexity

The Hundred Days of Sara Mata: Explaining Unnatural Death in Vanuatu

1984 ◽  
Vol 14 (2) ◽  
pp. 135-144
Author(s):  
Margaret Rodman ◽  
William Rodman
Keyword(s):  
Dynamic Complexity ◽  
Process Of Change ◽  
Unnatural Death ◽  
Structural Principles

Who or what killed Sara Mata? During the hundred days of mourning that followed the young woman's “unnatural” death, residents of Aoba, an island in Vanuatu, sought to discover the cause of Sara's death. Alternative local explanations of the death highlight the ambiguity that characterizes Aoban beliefs about people's ability to cause death by supernatural means. We show the conventional anthropological categories of poison, sorcery, and witchcraft may misrepresent the dynamic complexity of such indigenous beliefs. Finally, we discuss a process of change in Aoban ideas concerning unnatural death, a shift from a belief in sorcery to a belief in self-destruction by supernatural means. The possibility that a society can “rewrite” a transitive process of sorcery into a reflexive mode raises new questions about the theoretical relations between witchcraft, sorcery, and structural principles of society.

scholarly journals Towards efficient verification of population protocols

2021 ◽  
Author(s):  
Michael Blondin ◽  
Javier Esparza ◽  
Stefan Jaax ◽  
Philipp J. Meyer
Keyword(s):  
Linear Constraints ◽  
Computational Power ◽  
High Complexity ◽  
Reachability Problem ◽  
Population Protocols ◽  
Finite State ◽  
State Agents ◽  
Efficient Verification ◽  
Primitive Recursive ◽  
Very High

AbstractPopulation protocols are a well established model of computation by anonymous, identical finite-state agents. A protocol is well-specified if from every initial configuration, all fair executions of the protocol reach a common consensus. The central verification question for population protocols is the well-specification problem: deciding if a given protocol is well-specified. Esparza et al. have recently shown that this problem is decidable, but with very high complexity: it is at least as hard as the Petri net reachability problem, which is -hard, and for which only algorithms of non-primitive recursive complexity are currently known. In this paper we introduce the class $${ WS}^3$$ WS 3 of well-specified strongly-silent protocols and we prove that it is suitable for automatic verification. More precisely, we show that $${ WS}^3$$ WS 3 has the same computational power as general well-specified protocols, and captures standard protocols from the literature. Moreover, we show that the membership and correctness problems for $${ WS}^3$$ WS 3 reduce to solving boolean combinations of linear constraints over $${\mathbb {N}}$$ N . This allowed us to develop the first software able to automatically prove correctness for all of the infinitely many possible inputs.

Sketches of Dynamic Complexity

2020 ◽  
Vol 49 (2) ◽  
pp. 18-29
Author(s):  
Thomas Schwentick ◽  
Nils Vortmeier ◽  
Thomas Zeume
Keyword(s):  
Dynamic Complexity

scholarly journals Reachability Problems on Reliable and Lossy Queue Automata

2021 ◽  
Author(s):  
Chris Köcher
Keyword(s):  
Polynomial Time ◽  
Reachability Problem ◽  
Single Sequence

AbstractWe study the reachability problem for queue automata and lossy queue automata. Concretely, we consider the set of queue contents which are forwards resp. backwards reachable from a given set of queue contents. Here, we prove the preservation of regularity if the queue automaton loops through some special sets of transformation sequences. This is a generalization of the results by Boigelot et al. and Abdulla et al. regarding queue automata looping through a single sequence of transformations. We also prove that our construction is possible in polynomial time.

scholarly journals Configurable verification of timed automata with discrete variables

2020 ◽  
Author(s):  
Tamás Tóth ◽  
István Majzik
Keyword(s):  
Timed Automata ◽  
Empirical Evaluation ◽  
Real Time Systems ◽  
Discrete Variables ◽  
Reachability Problem ◽  
Abstraction Refinement ◽  
Dependent Behavior ◽  
Wide Range ◽  
Time Systems ◽  
Lazy Abstraction

AbstractAlgorithms and protocols with time dependent behavior are often specified formally using timed automata. For practical real-time systems, besides real-valued clock variables, these specifications typically contain discrete data variables with nontrivial data flow. In this paper, we propose a configurable lazy abstraction framework for the location reachability problem of timed automata that potentially contain discrete variables. Moreover, based on our previous work, we uniformly formalize in our framework several abstraction refinement strategies for both clock and discrete variables that can be freely combined, resulting in many distinct algorithm configurations. Besides the proposed refinement strategies, the configurability of the framework allows the integration of existing efficient lazy abstraction algorithms for clock variables based on $${\textit{LU}}$$ LU -bounds. We demonstrate the applicability of the framework and the proposed refinement strategies by an empirical evaluation on a wide range of timed automata models, including ones that contain discrete variables or diagonal constraints.

Dynamic Complexity Measures for Use in Complexity-Based System Design

2017 ◽  
Vol 11 (4) ◽  
pp. 2018-2027 ◽  
Author(s):  
Jonathan Fischi ◽  
Roshanak Nilchiani ◽  
Jon Wade
Keyword(s):  
System Design ◽  
Dynamic Complexity ◽  
Complexity Measures

scholarly journals The dynamic complexity of the TRPC1 channelosome

Channels ◽  
2011 ◽  
Vol 5 (5) ◽  
pp. 424-431 ◽  
Author(s):  
Hwei Ling Ong ◽  
Indu S. Ambudkar
Keyword(s):  
Dynamic Complexity

scholarly journals Beyond genetics – The emerging role of epigenetics and its clinical aspects

2012 ◽  
Vol 153 (6) ◽  
pp. 214-221 ◽  
Author(s):  
Veronika Urbán S. ◽  
Elizabeta Benevolenskaya ◽  
Judit Kiss ◽  
Bernadett Sági ◽  
Beáta Hegyi ◽  
...  
Keyword(s):  
Decisive Role ◽  
Clinical Aspects ◽  
Dynamic Complexity ◽  
Spatial Changes ◽  
Future Drug ◽  
A Cell ◽  
Multiple Cell ◽  
Induced Changes ◽  
Cell Phenotypes ◽  
Diversity Of Life

Analysis of genomic sequences has clearly shown that the genomic differences among species do not explain the diversity of life. The genetic code itself serves as only a part of the dynamic complexity that results in the temporal and spatial changes in cell phenotypes during development. It has been concluded that the phenotype of a cell and of the organism as a whole is more influenced by environmentally-induced changes in gene activity than had been previously thought. The emerging field of epigenetics focuses on molecular marks on chromatin; called the epigenome, which serve as transmitters between the genome and the environment. These changes not only persist through multiple cell division cycles, but may also endure for multiple generations. Irregular alterations of the epigenome; called epimutations, may have a decisive role in the etiology of human pathologies such as malignancies and other complex human diseases. Epigenetics can provide the missing link between genetics, disease and the environment. Therefore, this field may have an increasing impact on future drug design and serve as a basis for new therapeutic/preventative approaches. Orv. Hetil., 2012, 153, 214–221.

scholarly journals The Dynamic Complexity of a Holling Type-IV Predator-Prey System with Stage Structure and Double Delays

2011 ◽  
Vol 2011 ◽  
pp. 1-19 ◽  
Author(s):  
Yakui Xue ◽  
Xiafeng Duan
Keyword(s):  
Time Delay ◽  
Equilibrium Point ◽  
Dynamical Behavior ◽  
Stage Structure ◽  
Point Of View ◽  
Maturation Time ◽  
Dynamic Complexity ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Type Iv

We invest a predator-prey model of Holling type-IV functional response with stage structure and double delays due to maturation time for both prey and predator. The dynamical behavior of the system is investigated from the point of view of stability switches aspects. We assume that the immature and mature individuals of each species are divided by a fixed age, and the mature predator only attacks the mature prey. Based on some comparison arguments, sharp threshold conditions which are both necessary and sufficient for the global stability of the equilibrium point of predator extinction are obtained. The most important outcome of this paper is that the variation of predator stage structure can affect the existence of the interior equilibrium point and drive the predator into extinction by changing the maturation (through-stage) time delay. Our linear stability work and numerical results show that if the resource is dynamic, as in nature, there is a window in maturation time delay parameters that generate sustainable oscillatory dynamics.

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