Isomorphism of Computable Structures and Vaught's Conjecture

2013 ◽  
Vol 78 (4) ◽  
pp. 1328-1344 ◽  
Author(s):  
Howard Becker
Keyword(s):  
Negative Answer ◽  
Isomorphism Type ◽  
Computable Structures

AbstractThe following question is open: Does there exist a hyperarithmetic class of computable structures with exactly one non-hyperarithmetic isomorphism-type? Given any oracle α ∈ 2ω, we can ask the same question relativized to α. A negative answer for every α implies Vaught's Conjecture for Lω1ω.

Singularities

2018 ◽  
Author(s):  
S. G. Rajeev
Keyword(s):  
Stokes Equations ◽  
Negative Answer ◽  
Three Dimensions ◽  
Picard Iteration ◽  
Navier Stokes ◽  
Scale Invariant ◽  
Navier Stokes Equations ◽  
L2 Norm ◽  
Two Dimensional Flow ◽  
Physical Consequences

The initial value problem of the incompressible Navier–Stokes equations is explained. Leray’s classic study of it (using Picard iteration) is simplified and described in the language of physics. The ideas of Lebesgue and Sobolev norms are explained. The L2 norm being the energy, cannot increase. This gives sufficient control to establish existence, regularity and uniqueness in two-dimensional flow. The L3 norm is not guaranteed to decrease, so this strategy fails in three dimensions. Leray’s proof of regularity for a finite time is outlined. His attempts to construct a scale-invariant singular solution, and modern work showing this is impossible, are then explained. The physical consequences of a negative answer to the regularity of Navier–Stokes solutions are explained. This chapter is meant as an introduction, for physicists, to a difficult field of analysis.

scholarly journals Some inequalities for star duality of the radial Blaschke-Minkowski homomorphisms

2020 ◽  
Vol 18 (1) ◽  
pp. 1064-1075
Author(s):  
Xia Zhao ◽  
Weidong Wang ◽  
Youjiang Lin
Keyword(s):  
Negative Answer ◽  
Positive Form ◽  
Dual Quermassintegrals ◽  
Monotonic Inequality ◽  
Star Bodies

Abstract In 2006, Schuster introduced the radial Blaschke-Minkowski homomorphisms. In this article, associating with the star duality of star bodies and dual quermassintegrals, we establish Brunn-Minkowski inequalities and monotonic inequality for the radial Blaschke-Minkowski homomorphisms. In addition, we consider its Shephard-type problems and give a positive form and a negative answer, respectively.

scholarly journals Π10 classes and strong degree spectra of relations

2007 ◽  
Vol 72 (3) ◽  
pp. 1003-1018 ◽  
Author(s):  
John Chisholm ◽  
Jennifer Chubb ◽  
Valentina S. Harizanov ◽  
Denis R. Hirschfeldt ◽  
Carl G. Jockusch ◽  
...  
Keyword(s):  
Kolmogorov Complexity ◽  
Initial Segment ◽  
Truth Table ◽  
Linear Ordering ◽  
Computable Structures ◽  
Degree Spectra

AbstractWe study the weak truth-table and truth-table degrees of the images of subsets of computable structures under isomorphisms between computable structures. In particular, we show that there is a low c.e. set that is not weak truth-table reducible to any initial segment of any scattered computable linear ordering. Countable subsets of 2ω and Kolmogorov complexity play a major role in the proof.

Where did Italian peasants live?

1979 ◽  
Vol 25 ◽  
pp. 1-25 ◽  
Author(s):  
P.D.A. Garnsey
Keyword(s):  
Characteristic Feature ◽  
Rural Economy ◽  
Negative Answer ◽  
Second Century ◽  
Small Farmers ◽  
Scholarly Literature ◽  
Wage Labour ◽  
Economic Forces ◽  
Tenant Farmers ◽  
The Impact

Until recently this was a question that was not asked. It was not asked because there was a prior question that was asked, and that received a negative answer: Did peasant proprietors survive in significant numbers in the late Republic or early Empire?The consensus of opinion has been that they were always to be found, but that they were relatively few. As the traditional rural economy of which they had been the characteristic feature gave way under the impact of new economic forces, they became a residual phenomenon. Moreover, this development had already occurred by the late second century B.C.It is to be noted that peasant proprietors, small farmers working the land they owned, rather than free cultivators as a whole, have usually been the object of inquiry. The roles of tenancy in the late Republic and of wage labour in all periods have rarely been positively evaluated. Again, the idea that small ownercultivators, tenant-farmers and day-labourers were overlapping categories in ancient Italy has been little developed in the scholarly literature.

Kallikrein blood system in acute respiratory diseases with bronchial obstruction syndrome in children

1982 ◽  
Vol 63 (4) ◽  
pp. 26-29
Author(s):  
V. A. Anokhin
Keyword(s):  
Respiratory Tract ◽  
Respiratory Diseases ◽  
Inhibitory Effect ◽  
Negative Answer ◽  
Blood System ◽  
Pulmonary Mechanics ◽  
Bronchial Obstruction ◽  
Ciliated Epithelium ◽  
Kinin System ◽  
Acute Respiratory Diseases

The activation of the kinin system of the blood in diseases of the respiratory system leads to an increase in the inflammatory response in the respiratory tract, causes bronchospasm to a large extent, and has an inhibitory effect on the function of the ciliated epithelium. There are no unequivocal judgments about the therapeutic effect of prednisolone in obstructive bronchitis and bronchiolitis in the literature. There is a negative answer to this question. At the same time, the beneficial effect of corticosteroids on pulmonary mechanics in bronchiolitis was noted.

Why Perfect Tests May Not Be Worth Waiting For: Information as a Commodity

2021 ◽  
Author(s):  
K. Drakopoulos ◽  
R. S. Randhawa
Keyword(s):  
Operations Management ◽  
Heterogeneous Agents ◽  
Negative Answer ◽  
Social Planner ◽  
Test Accuracy ◽  
Medical Testing ◽  
Additional Information ◽  
Course Of Action ◽  
Information Products ◽  
Limited Supply

Information products provide agents with additional information that can be used to update actions. In many situations, access to such products can be quite limited. For instance, in epidemics, there tends to be a limited supply of medical testing kits, or tests. These tests are information products because their output of a positive or a negative answer informs individuals and authorities on the underlying state and the appropriate course of action. In this paper, using an analytical model, we show how the accuracy of a test in detecting the underlying state affects the demand for the information product differentially across heterogeneous agents. Correspondingly, the test accuracy can serve as a rationing device to ensure that the limited supply of information products is appropriately allocated to the heterogeneous agents. When test availability is low and the social planner is unable to allocate tests in a targeted manner to the agents, we find that moderately good tests can outperform perfect tests in terms of social outcome. This paper was accepted by Charles Corbett, operations management.

scholarly journals Infinite limits and folding

2005 ◽  
Vol DMTCS Proceedings vol. AE,... (Proceedings) ◽  
Author(s):  
Anthony Bonato ◽  
Jeannette Janssen
Keyword(s):  
Biological Networks ◽  
Infinite Graphs ◽  
Isomorphism Type ◽  
Connected Component ◽  
Induced Subgraph ◽  
Pursuit Games ◽  
Graph Homomorphisms ◽  
International Audience

International audience We study infinite limits of graphs generated by the duplication model for biological networks. We prove that with probability 1, the sole nontrivial connected component of the limits is unique up to isomorphism. We describe certain infinite deterministic graphs which arise naturally from the model. We characterize the isomorphism type and induced subgraph structure of these infinite graphs using the notion of dismantlability from the theory of vertex pursuit games, and graph homomorphisms.

scholarly journals Building an integrated poverty measure by three poverty profiles

POPULATION ◽  
2019 ◽  
Vol 22 (1) ◽  
pp. 92-105
Author(s):  
Vladislav Zharomsky
Keyword(s):  
Structural Analysis ◽  
Poverty Line ◽  
Negative Answer ◽  
Subjective Perception ◽  
Absolute Poverty ◽  
Poverty Measure ◽  
Number Of Children ◽  
Parents And Children ◽  
Subsistence Minimum ◽  
Statistical Survey

On the basis of estimating three poverty profiles calculated on sample surveys data, the article presents the methods for obtaining an integrated poverty measure, which solves the model of latent structural analysis with binary classes. In such surveys as Parents and Children, Men and Women in Family, HSE Russian Longitudinal Monitoring Survey, Russian Household Budget Survey, there are questions characterizing different profiles of poverty — economic, deprivation and subjective. The last-mentioned profile presents a subjective perception of one’s position on the scale of living standards. Estimates by the three profiles measure different sides of poverty, but it is not clear how they are harmonized, and whether latent poverty is statistically reflected in them. The model of the latent structural analysis may give a positive or negative answer to this question. In case of the positive answer it is proposed to take the probability of latent poverty as an integrated poverty measure. The article provides the results of calculations for three groups of households: those of pensioners, of able-bodied persons, and mixed households consisting of pensioners and the able-bodied. On the data from the largest Rosstat survey — Statistical Survey of Income and Participation in Social Programs (VNDN) were made estimates of latent poverty for urban and rural population of Russia, for households with different number of children. It shows that latent poverty and coherence of different population groups are not contrary to the meaningful views on the phenomenon. It is found out that the understated size of the subsistence minimum (absolute poverty line) leads to lack of coherence between three estimates for households of pensioners. In this case, feeling of poverty and deprivation levels are not in line with the economic estimation of poverty.

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