Topology of geometric joins

We consider the geometric join of a family of subsets of the Euclidean space. This is a construction frequently used in the (colorful) Carath\'eodory and Tverberg theorems, and their relatives. We conjecture that when the family has at least $d+1$ sets, where $d$ is the dimension of the space, then the geometric join is contractible. We are able to prove this when $d$ equals $2$ and $3$, while for larger $d$ we show that the geometric join is contractible provided the number of sets is quadratic in $d$. We also consider a matroid generalization of geometric joins and provide similar bounds in this case

Reform Redux: Measurement, Determinants and Reversals

We construct objective measures of privatization, internal and external liberalization reform efforts, across countries over time, and investigate their determinants, reversals and macroeconomic impacts. We find that GDP growth determines external liberalization and privatization, concentration of political power drives internal liberalization, and democracy underpins all three. We find that FDI inflows reduce the probability of privatization reversals, labour strikes increase that of internal liberalization reversals, and terms of trade shocks increase that of external liberalization reversals. We replicate previous studies and find that the macroeconomic effects of reform (when measured objectively) tend to be larger and more precisely estimated.reform; liberalization; privatization; political economy; transition

Reform Redux: Measurement, Determinants and Reversals

What do we know about the effects of structural reforms? One main reason the answer may be “little†is inadequate measurement. In this paper we put forward improved measures of economic liberalization across countries over time. We show that structural reforms, carefully measured, follow richer dynamics (than those from existing indexes) which are very closely linked to the theoretical work. For example, we find FDI inflows reduce the likelihood of privatization reversals and labour strikes increase that of price liberalization reversals. We also find that our new measures, in standard specifications, have larger and more precisely estimated impacts on growth.Structural reforms, reform reversals, price liberalization, trade liberalization, privatization, political economy.

Temporalising OWL 2 QL

We design a temporal description logic, TQL, that extends the standard ontology language OWL2QL, provides basic means for temporal conceptual modelling and ensures first-order rewritability of conjunctive queries for suitably defined data instances with validity time

Results of experiments to simulate radiant heating of propellant in a nuclear light bulb engine using a D-C arc radiant energy source

Simulating radiant heating of propellant stream of nuclear light bulb engin

Temporal description logic for ontology-based data access

Our aim is to investigate ontology-based data access over temporal data with validity time and ontologies capable of temporal conceptual modelling. To this end, we design a temporal description logic, TQL, that extends the standard ontology language OWL2QL, provides basic means for temporal conceptual modelling and ensures first-order rewritability of conjunctive queries for suitably defined data instances with validity time