10,920 research outputs found
Finite Open-World Query Answering with Number Restrictions (Extended Version)
Open-world query answering is the problem of deciding, given a set of facts,
conjunction of constraints, and query, whether the facts and constraints imply
the query. This amounts to reasoning over all instances that include the facts
and satisfy the constraints. We study finite open-world query answering (FQA),
which assumes that the underlying world is finite and thus only considers the
finite completions of the instance. The major known decidable cases of FQA
derive from the following: the guarded fragment of first-order logic, which can
express referential constraints (data in one place points to data in another)
but cannot express number restrictions such as functional dependencies; and the
guarded fragment with number restrictions but on a signature of arity only two.
In this paper, we give the first decidability results for FQA that combine both
referential constraints and number restrictions for arbitrary signatures: we
show that, for unary inclusion dependencies and functional dependencies, the
finiteness assumption of FQA can be lifted up to taking the finite implication
closure of the dependencies. Our result relies on new techniques to construct
finite universal models of such constraints, for any bound on the maximal query
size.Comment: 59 pages. To appear in LICS 2015. Extended version including proof
Fields and Fusions: Hrushovski constructions and their definable groups
An overview is given of the various expansions of fields and fusions of
strongly minimal sets obtained by means of Hrushovski's amalgamation method, as
well as a characterization of the groups definable in these structures
Wages, patronage and welfare:Thrift and its limits in Argentina’s Gran Chaco
In Argentina’s Gran Chaco, Indigenous Guaranà households ensure their subsistence through the skillful management of wages, patronage, and welfare. This chapter explores the extent to which thrift and anti-thrift characterize Guaranà engagements with resource flows. In a context marked by unemployment and a dwindling frontier economy, the chapter shows the gendered social relations through which resources are elicited, sourced, managed and spent. The Guaranà case demonstrates how the boundaries between thrift and anti-thrift are blurred in everyday life and illustrates how the different scales and temporalities of resource flows articulate households, settlements, extractive economies, and democratic politics
Mitochondrial haplogroups associated with elite Japanese athlete status
Purpose It has been hypothesised that certain mitochondrial haplogroups, which are defined by the presence of a characteristic cluster of tightly linked mitochondrial DNA polymorphisms, would be associated with elite Japanese athlete status. To examine this hypothesis, the frequencies of mitochondrial haplogroups found in elite Japanese athletes were compared with those in the general Japanese population. Methods Subjects comprised 139 Olympic athletes (79 endurance/middle-power athletes (EMA), 60 sprint/power athletes (SPA)) and 672 controls (CON). Two mitochondrial DNA fragments containing the hypervariable sequence I (m16024-m16383) of the major non-coding region and the polymorphic site at m. 5178C>A within the NADH dehydrogenase subunit 2 gene were sequenced, and subjects were classified into 12 major mitochondrial haplogroups (ie, F, B, A, N9a, N9b, M7a, M7b, M*, G2, G1, D5 or D4). The mitochondrial haplogroup frequency differences among EMA, SPA and CON were then examined. Results EMA showed an excess of haplogroup G1 (OR 2.52, 95% CI 1.05 to 6.02, p=0.032), with 8.9% compared with 3.7% in CON, whereas SPA displayed a greater proportion of haplogroup F (OR 2.79, 95% CI 1.28 to 6.07, p=0.007), with 15.0% compared with 6.0% in CON. Conclusions The results suggest that mitochondrial haplogroups G1 and F are associated with elite EMA and SPA status in Japanese athletes, respectivel
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