On The Relational Width of First-Order Expansions of Finitely Bounded Homogeneous Binary Cores with Bounded Strict Width

The relational width of a finite structure, if bounded, is always (1,1) or (2,3). In this paper we study the relational width of first-order expansions of finitely bounded homogeneous binary cores where binary cores are structures with equality and some anti-reflexive binary relations such that for any two different elements a, b in the domain there is exactly one binary relation R with (a, b) in R. Our main result is that first-order expansions of liberal finitely bounded homogeneous binary cores with bounded strict width have relational width (2, MaxBound) where MaxBound is the size of the largest forbidden substructure, but is not less than 3, and liberal stands for structures that do not forbid certain finite structures of small size. This result is built on a new approach and concerns a broad class of structures including reducts of homogeneous digraphs for which the CSP complexity classification has not yet been obtained.Comment: A long version of an extended abstract that appeared in LICS 202

Relational Width of First-Order Expansions of Homogeneous Graphs with Bounded Strict Width

Solving the algebraic dichotomy conjecture for constraint satisfaction problems over structures first-order definable in countably infinite finitely bounded homogeneous structures requires understanding the applicability of local-consistency methods in this setting. We study the amount of consistency (measured by relational width) needed to solve CSP(?) for first-order expansions ? of countably infinite homogeneous graphs ? := (A; E), which happen all to be finitely bounded. We study our problem for structures ? that additionally have bounded strict width, i.e., for which establishing local consistency of an instance of CSP(?) not only decides if there is a solution but also ensures that every solution may be obtained from a locally consistent instance by greedily assigning values to variables, without backtracking. Our main result is that the structures ? under consideration have relational width exactly (2, ?_?) where ?_? is the maximal size of a forbidden subgraph of ?, but not smaller than 3. It beats the upper bound: (2 m, 3 m) where m = max(arity(?)+1, ?, 3) and arity(?) is the largest arity of a relation in ?, which follows from a sufficient condition implying bounded relational width given in [Manuel Bodirsky and Antoine Mottet, 2018]. Since ?_? may be arbitrarily large, our result contrasts the collapse of the relational bounded width hierarchy for finite structures ?, whose relational width, if finite, is always at most (2,3)

Offshoring tasks, yet creating jobs?

The policy debate views offshoring as job destruction. Theoretical models of offshoring mostly assume full employment. We develop a model of task trade that allows for equilibrium unemployment. In this model, there are two margins of adjustment. At the extensive margin, moving tasks offshore destroys jobs. At the intensive margin, due to higher productivity of labor in domestic tasks it creates jobs. Exploring these conditions in detail, we identify the potential of non-monotonic adjustment: Early stages of offshoring always lead to higher unemployment, while later stages may entail net job creation. We highlight this potential through numerical simulations. --Offshoring,Trade in Tasks,Unemployment,Non-monotonicity

Two-way migration between similar countries

We develop a model to explain two-way migration of high-skilled individuals between countries that are similar in their economic characteristics. High-skilled migration is explained by a combination of two features: In both countries there is a continuum of workers with differing abilities, which are private knowledge, and the production technology gives incentives to firms for hiring workers of similar ability. In the presence on migration cost, high-skilled workers self-select into the group of migrants, thereby ensuring they are hired together with other high-skilled migrants. The laissez-faire equilibrium features too much migration, explained by a negative migration externality, and as a result all individuals are worse of than in autarky. We also show that for suffciently low levels of migration cost the optimal level of migration is strictly positive. In extensions to our basic model, we consider the presence of an internationally immobile factor and find that in this case the possibility of aggregate gains from migration in the laissez-faire equilibrium emerges. We also show that our basic results are robust with respect to small differences in countries' technologies. --Migration,Skilled Workers,Positive Assortative Matching,Externalities

Le développement de la construction touristique et de repos dans les Bieszczady Polonaises

W artykule przedstawiono zarys rozwoju budownictwa turystyczno-wypoczynkowego w Bieszczadach Polskich z podziałem na dwa okresy: przedwojenny i powojenny. Autor omawia powstanie ważniejszych obiektów turystycznych, charakteryzując ich lokalizację oraz standard. Pracę kończy ogólna analiza współczesnego rozmieszczenia obiektów turystycznych w polskiej części Bieszczadów

Poczucie wsparcia otrzymywanego a oczekiwanego przez rodziców dzieci niepełnosprawnych na przykładzie działań lokalnych w szkole podstawowej

The aim of the study is to determine a space and process of support for parents of children with disabilities, as well as an indication of the neglected areas in the organization of early intervention in Poland. The characteristics of this space relates primarily to the place and role of people taking an active part in the process of support: parents and therapists and their relationship with a disabled child. Considerations revolve around descriptions of various models of assistance provided to families in the process of early intervention

Prion Epidemiology And The Npdpsc’s Experience With Rt-Quic

Prion diseases, or transmissible spongiform encephalopathies, constitute a wide array of invariably fatal rapidly progressive neurodegenerative illnesses that affect both humans and animals. The gold standard of diagnosis for these diseases is through neuropathologic examination of brain tissue following autopsy. In September 2018, the Centers for Disease Control and Prevention (CDC) added positive real-time quaking-induced conversion (RT-QuIC) test result as a likely indicator of certain human prion diseases. With high sensitivity and specificity approaching 100%, RT-QuIC has quickly become one of the most powerful antemortem diagnostic tools. This paper will demonstrate why changes in diagnostic criteria and reporting metrics are appropriate and innovative in the diagnosis and surveillance of prion disease. An introduction to prion biology and epidemiology in the 21st century is followed by the presentation of the National Prion Disease Pathology Surveillance Center’s (NPDPSC) experience with 2nd generation RT-QuIC over a 3-year period. In this observational study, 10,498 unique cerebrospinal fluid (CSF) samples taken from suspected cases of prion disease were sent to the NPDPSC. 567 of these cases also went on to autopsy; autopsy results were then used to determine RT-QuIC’s sensitivity (90.3%) and specificity (99.8%). Type of prion disease, illness duration, and various demographic characteristics were analyzed to determine possible influences on RT-QuIC results. Sensitivity was found to be lower among rarer prion diseases, such as genetic and atypical sporadic diseases. Poor sample quality was also associated with lower sensitivity. Sporadic Creutzfeldt-Jakob Disease (sCJD) cases were more likely to produce false negative RT-QuIC results if samples were from younger individuals or from cases with longer disease durations. In conclusion, RT-QuIC is a highly sensitive and specific test that can be an aid in ascertaining an extremely rare disease. However, this study has shown that its sensitivity and specificity can be affected by disease type, specimen quality, and demographic characteristics among individuals with suspected cases of prion disease. Moving forward, this novel assay will become an invaluable objective tool in diagnosing prion disease antemortem