4,219 research outputs found
Stability and Invariant Random Subgroups
Consider , endowed with the normalized Hamming metric
. A finitely-generated group is \emph{P-stable} if every almost
homomorphism (i.e.,
for every , ) is close to an actual
homomorphism .
Glebsky and Rivera observed that finite groups are P-stable, while Arzhantseva
and P\u{a}unescu showed the same for abelian groups and raised many questions,
especially about P-stability of amenable groups. We develop P-stability in
general, and in particular for amenable groups. Our main tool is the theory of
invariant random subgroups (IRS), which enables us to give a characterization
of P-stability among amenable groups, and to deduce stability and instability
of various families of amenable groups.Comment: 24 pages; v2 includes minor updates and new reference
Politicians' Outside Earnings and Electoral Competition
This paper deals with the impact of electoral competition on politicians' outside earnings. We propose a simple theoretical model with politicians facing a tradeoff between allocating their time to political effort or to an alternative use generating outside earnings. The model has a testable implication stating that the amount of time spent on outside work is negatively related to the degree of electoral competition. We test this implication using a new dataset on outside earnings of members of the German
federal assembly. Taking into account the potential endogeneity of measures of political competition that depend on past election outcomes, we find that politicians facing low competition have substantially higher outside earnings
Heterotic Non-Kahler Geometries via Polystable Bundles on Calabi-Yau Threefolds
In arXiv:1008.1018 it is shown that a given stable vector bundle on a
Calabi-Yau threefold which satisfies can be deformed to a
solution of the Strominger system and the equations of motion of heterotic
string theory. In this note we extend this result to the polystable case and
construct explicit examples of polystable bundles on elliptically fibered
Calabi-Yau threefolds where it applies. The polystable bundle is given by a
spectral cover bundle, for the visible sector, and a suitably chosen bundle,
for the hidden sector. This provides a new class of heterotic flux
compactifications via non-Kahler deformation of Calabi-Yau geometries with
polystable bundles. As an application, we obtain examples of non-Kahler
deformations of some three generation GUT models.Comment: 12 pages, late
Margins of Multinational Labor Substitution
Multinational labor demand responds to wage differentials at the extensive margin, when a multinational enterprise (MNE) expands into foreign locations, and at the intensive margin, when an MNE operates existing affiliates across locations. We derive conditions for parametric and nonparametric identification of an MNE model to infer elasticities of labor substitution at both margins, controlling for location selectivity. Prior studies have rarely found foreign wages or operations to affect employment. Our strategy detects salient adjustments at the extensive margin for German MNEs. With every percentage increase in German wages, German MNEs allocate 2,000 manufacturing jobs to Eastern Europe at the extensive margin and 4,000 jobs overall.multinational enterprise, location choice, sample selectivity, labor demand, translog cost function, nonparametric estimation
Politicians' outside earnings and electoral competition
This paper deals with the impact of electoral competition on politicians´ outside earnings. We propose a simple theoretical model with politicians facing a tradeoff between allocating their time to political effort or to an alternative use generating outside earnings. The model has a testable implication stating that the amount of time spent on outside work is negatively related to the degree of electoral competition. We test this implication using a new dataset on outside earnings of members of the German federal assembly. Taking into account the potential endogeneity of measures of political competition that depend on past election outcomes, we find that politicians facing low competition have substantially higher outside earnings. --Political competition,outside earnings,political rents
Margins of multinational labor substitution
Multinational labor demand responds to wage differentials at the extensive margin, when a multinational enterprise (MNE) expands into foreign locations, and at the intensive margin, when an MNE operates existing affiliates across locations. We derive conditions for parametric and nonparametric identification of an MNE model to infer elasticities of labor substitution at both margins, controlling for location selectivity. Prior studies rarely found foreign wages or operations to affect employment. Our strategy detects salient adjustments for German MNEs. With a one-percent increase in German wages, German MNEs add 2,000 manufacturing jobs in Eastern Europe at the extensive margin and 4,000 jobs overall; a converse one-percent drop in Eastern European wages is associated with an overall withdrawal of 730 MNE jobs from Germany. --Multinational enterprise,location choice,multiple sample selectivity,labor demand,translog cost function,nonparametric estimation
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