scholarly journals Reconstruction of Rooted Directed Trees

2019 ◽  
Vol 24 (2) ◽  
pp. 249-262
Author(s):  
Dénes Bartha
Keyword(s):  
Computer Search ◽  
Frequency Vector ◽  
Directed Tree ◽  
Frequency Vectors

Let T be a rooted directed tree on n vertices, rooted at v. The rooted subtree frequency vector (RSTF-vector) of T with root v, denoted by rstf(T, v) is a vector of length n whose entry at position k is the number of subtrees of T that contain v and have exactly k vertices. In this paper we present an algorithm for reconstructing rooted directed trees from their rooted subtree frequencies (up to isomorphism). We show that there are examples of nonisomorphic pairs of rooted directed trees that are RSTF-equivalent, s.t. they share the same rooted subtree frequency vectors. We have found all such pairs (groups) for small sizes by using exhaustive computer search. We show that infinitely many nonisomorphic RSTF-equivalent pairs of trees exist by constructing infinite families of examples.

Machine Learning of Motor Vehicle Accident Categories from Narrative Data

1996 ◽  
Vol 35 (04/05) ◽  
pp. 309-316 ◽  
Author(s):  
M. R. Lehto ◽  
G. S. Sorock
Keyword(s):  
Machine Learning ◽  
Bayesian Model ◽  
Keyword Search ◽  
Motor Vehicle ◽  
Motor Vehicle Accident ◽  
Computer Search ◽  
Vehicle Accident ◽  
Learning Technique ◽  
Expert Ratings ◽  
Keyword Searches

Abstract:Bayesian inferencing as a machine learning technique was evaluated for identifying pre-crash activity and crash type from accident narratives describing 3,686 motor vehicle crashes. It was hypothesized that a Bayesian model could learn from a computer search for 63 keywords related to accident categories. Learning was described in terms of the ability to accurately classify previously unclassifiable narratives not containing the original keywords. When narratives contained keywords, the results obtained using both the Bayesian model and keyword search corresponded closely to expert ratings (P(detection)≥0.9, and P(false positive)≤0.05). For narratives not containing keywords, when the threshold used by the Bayesian model was varied between p>0.5 and p>0.9, the overall probability of detecting a category assigned by the expert varied between 67% and 12%. False positives correspondingly varied between 32% and 3%. These latter results demonstrated that the Bayesian system learned from the results of the keyword searches.

Odontopleura (Trilobita, Silurian), and a method of constrained congruency analysis

1990 ◽  
Vol 64 (4) ◽  
pp. 600-614 ◽  
Author(s):  
Jonathan M. Adrain ◽  
Brian D. E. Chatterton
Keyword(s):  
Cladistic Analysis ◽  
Canadian Arctic ◽  
Wide Distribution ◽  
Parsimony Analysis ◽  
Directed Tree ◽  
Shelf Slope ◽  
Major Species ◽  
Species Groups ◽  
The Universe ◽  
A New Species

Odontopleura (Odontopleura) arctica, a new species of odontopleurine trilobite, is described from the Canadian Arctic. A method of cladistic analysis is detailed. Parsimony analysis should be performed treating all characters as unordered. The universe of directed trees implied by the resulting rootless network(s) can then be examined and a preferred tree selected by a criterion of congruency. Namely, the most parsimonious directed tree that accommodates the most congruent arrangement of character-states should be taken as the preferred cladogram. Since this is essentially a general congruency method operating within the constraints of parsimony, it is termed “constrained congruency.” The method is applied to the genus Odontopleura, resulting in the recognition of two major species groups, the nominate subgenus and Sinespinaspis n. subgen. Odontopleura (Ivanopleura) dufrenoyi Barrande is tentatively included in the genus, but considered too poorly known for cladistic analysis. Species assigned to Odontopleura (Odontopleura) include Odontopleura ovata Emmrich, Odontopleura brevigena Chatterton and Perry, Odontopleura (Odontopleura) arctica n. sp., and Diacanthaspis serotina Apollonov. Species assigned to Sinespinaspis n. subgen. include Taemasaspis llandoveryana Šnajdr, Odontopleura greenwoodi Chatterton and Perry, Odontopleura maccallai Chatterton and Perry, and Odontopleura nehedensis Chatterton and Perry. Odontopleura bombini Chatterton and Perry is tentatively placed in synonymy with Odontopleura nehedensis. The genus had a wide distribution throughout the Early and Middle Silurian, due to preferences for deep-water, distal shelf or shelf-slope transition zone habitats.

Falsification of Hybrid Systems Using Adaptive Probabilistic Search

2021 ◽  
Vol 31 (3) ◽  
pp. 1-22
Author(s):  
Gidon Ernst ◽  
Sean Sedwards ◽  
Zhenya Zhang ◽  
Ichiro Hasuo
Keyword(s):  
Hybrid Systems ◽  
Input Signal ◽  
Tree Search ◽  
Single Trial ◽  
Decision Point ◽  
Directed Tree ◽  
Probabilistic Choice ◽  
Original Algorithm ◽  
Fine Grained ◽  
Probabilistic Search

We present and analyse an algorithm that quickly finds falsifying inputs for hybrid systems. Our method is based on a probabilistically directed tree search, whose distribution adapts to consider an increasingly fine-grained discretization of the input space. In experiments with standard benchmarks, our algorithm shows comparable or better performance to existing techniques, yet it does not build an explicit model of a system. Instead, at each decision point within a single trial, it makes an uninformed probabilistic choice between simple strategies to extend the input signal by means of exploration or exploitation. Key to our approach is the way input signal space is decomposed into levels, such that coarse segments are more probable than fine segments. We perform experiments to demonstrate how and why our approach works, finding that a fully randomized exploration strategy performs as well as our original algorithm that exploits robustness. We propose this strategy as a new baseline for falsification and conclude that more discriminative benchmarks are required.

40‐MHz high‐frequency vector Doppler imaging for superficial venous valve flow estimation

2020 ◽  
Vol 47 (9) ◽  
pp. 4020-4031
Author(s):  
Hsin Huang ◽  
Pei‐Yu Chen ◽  
Chih‐Chung Huang
Keyword(s):  
High Frequency ◽  
Doppler Imaging ◽  
Frequency Vector ◽  
Venous Valve ◽  
Flow Estimation

A New Category of Three-Dimensional Chaotic Flows with Identical Eigenvalues

2020 ◽  
Vol 30 (02) ◽  
pp. 2050026 ◽  
Author(s):  
Zahra Faghani ◽  
Fahimeh Nazarimehr ◽  
Sajad Jafari ◽  
Julien C. Sprott
Keyword(s):  
Chaotic Systems ◽  
Autonomous Systems ◽  
Three Dimensional ◽  
Special Property ◽  
Computer Search ◽  
Chaotic Flows ◽  
Stable Equilibria ◽  
Dynamical Properties ◽  
Simple Systems ◽  
First Time

In this paper, some new three-dimensional chaotic systems are proposed. The special property of these autonomous systems is their identical eigenvalues. The systems are designed based on the general form of quadratic jerk systems with 10 terms, and some systems with stable equilibria. Using a systematic computer search, 12 simple chaotic systems with identical eigenvalues were found. We believe that systems with identical eigenvalues are described here for the first time. These simple systems are listed in this paper, and their dynamical properties are investigated.

scholarly journals Non-isomorphic 2-perfect 6-cycle systems of order 13

1991 ◽  
Vol 44 (3) ◽  
pp. 381-385 ◽  
Author(s):  
Rebecca A.H. Gower
Keyword(s):  
Computer Search ◽  
Cycle Systems

Running a computer search for new, cyclic, 2-perfect 6-cycle systems of order 13 and constructing the quasigroups which arise from such systems enabled the author to establish that there are at most two such non-isomorphic systems. Then by using two-variable laws of the quasigroups it is shown that there are exactly two non-isomorphic 2-perfect 6-cycle systems of order 13 which are cyclic.

Evidence for a separate type of migraine with aura

Neurology ◽  
2003 ◽  
Vol 60 (4) ◽  
pp. 595-601 ◽  
Author(s):  
Lise L. Thomsen ◽  
Elsebet Ostergaard ◽  
Jes Olesen ◽  
Michael B. Russell
Keyword(s):  
Migraine With Aura ◽  
Telephone Interview ◽  
Clinical Symptoms ◽  
Familial Hemiplegic Migraine ◽  
Computer Search ◽  
Hemiplegic Migraine ◽  
Motor Weakness ◽  
National Patient Register ◽  
National Patient ◽  
Sequential Appearance

Objective: To compare clinical characteristics of patients with sporadic hemiplegic migraine (SHM) with those of patients with migraine with typical aura (MA) and patients with familial hemiplegic migraine (FHM).Methods: The authors used a computer search of Denmark’s National Patient Register to screen the population for patients with migraine with aura with motor weakness, and also examined case records from headache clinics and private practicing neurologists and placed advertisements. The authors screened patients and their relatives with a semi-structured validated telephone interview. All recruited patients were then interviewed by a physician and given a neurologic examination.Results: A total of 105 patients with SHM were identified. Seventy-two percent had four typical aura symptoms: visual, sensory, aphasic, and motor. All had at least two symptoms present during SHM attacks. A gradual progression and sequential appearance of aura symptoms was typical; compared with MA, the duration of each aura symptom was usually prolonged and bilateral motor symptoms were more frequent. Of the patients with SHM, 72% fulfilled the criteria for basilar migraine during SHM attacks. The aura was usually followed by headache, as is common in FHM but not MA.Conclusions: Patients with sporadic hemiplegic migraine had clinical symptoms identical to familial hemiplegic migraine and significantly different from migraine with typical aura. Sporadic hemiplegic migraine is a separate entity, and should be classified with familial hemiplegic migraine.

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