The Role of "Skill Enhancing Trade" in Brazil: Some Evidence from Microdata

Brazil was characterised by a marked process of trade liberalisation in the 1990s, resulting in a dramatic increase in the volumes of exports and imports since the year 2000. Over the same period, the relative demand for skilled labour has increased substantially. To investigate whether these two simultaneous phenomena are linked is the purpose of this paper. More in particular, this study focuses on the impact of trade openness and technology transfer on the relative demand for skilled labour in Brazilian manufacturing firms, using a unique panel database (resulting from merging three different statistical sources) of Brazilian manufacturing firms over the period 1997-2005. Descriptive statistics show that the increase in the relative demand for skilled labour was mainly driven by the within-industry variation, supporting the hypothesis that technology (and in particular technological transfer from richer countries) may have played a role in determining the skill-upgrading of Brazilian manufacturing firms. The econometric results further support this hypothesis. Indeed, the estimations show that domestic capital is a complement of the skilled workers and that imported capital goods clearly act as a skill-enhancing component of trade. Hence, our results support the view that embodied technological change through the importation of capital goods has involved a clear skill-biased impact in Brazilian manufacturing.skill-enhancing trade, skill-bias, panel data, Brazil

Provably Correct Floating-Point Implementation of a Point-In-Polygon Algorithm

The problem of determining whether or not a point lies inside a given polygon occurs in many applications. In air traffic management concepts, a correct solution to the point-in-polygon problem is critical to geofencing systems for Unmanned Aerial Vehicles and in weather avoidance applications. Many mathematical methods can be used to solve the point-in-polygon problem. Unfortunately, a straightforward floating- point implementation of these methods can lead to incorrect results due to round-off errors. In particular, these errors may cause the control flow of the program to diverge with respect to the ideal real-number algorithm. This divergence potentially results in an incorrect point-in- polygon determination even when the point is far from the edges of the polygon. This paper presents a provably correct implementation of a point-in-polygon method that is based on the computation of the winding number. This implementation is mechanically generated from a source- to-source transformation of the ideal real-number specification of the algorithm. The correctness of this implementation is formally verified within the Frama-C analyzer, where the proof obligations are discharged using the Prototype Verification System (PVS)