SOLVING THE JIGSAW PUZZLE PROBLEM IN LINEAR TIME

Abstract

We introduce an algorithm that efficiently matches (fits together) parts of boundaries of two-dimensional objects in order to assemble apictorial jigsaw puzzles. A rotation-independent shape encoding allows us to find the best (longest) match between two shapes in time proportional to the sum of the lengths of their representations. In order to find this match, we use Weiner's string matching technique combined with compact position trees to find, in linear time, the longest shared pattern between two strings. The shape matching procedure is then used by two greedy algorithms to assemble the apictorial jigsaw puzzles.     

Bilateral Resource Redeployment and Capabilities Improvement Following Horizontal Acquisitions

This paper studies the incidence and impact of bilateral redeploymentof resources between target and acquiring firms following 253horizontal acquisitions involving North American and Europeanfirms between 1988 and 1992. The resources include ten typesof technical, commercial, administrative and financial resources.We find that acquisitions often involve substantial technicaland commercial integration of the resources of the acquirerand target, while representing managerial and financial expansionof the acquirer rather than the target. In turn, we show thatbilateral redeployment improves five types of capabilities ofthe acquiring and target businesses, induding R&D capabilities,time to market, product quality, product cost and output flexibility.The empirical implications support the conceptual argument thatacquisitions play a key role in business adaptation.     

ABA during reproductive development in non-irrigated grapevines (Vitis vinifera L. cv. Tempranillo)

In grapevines, stomatal aperture decreases after a mid-morning peak during summer days. Afternoon stomatal closure increases in non-irrigated plants as water limitation progresses, which suggests the involvement of abscisic acid (ABA) in the control of stomatal aperture. The objective of this work was to study the seasonal and diurnal time-courses of CO₂ assimilation rate, leaf conductance, leaf water potential +, and ABA concentration in xylem sap, leaves, flowers and berries in non-irrigated field-grown Tempranillo grapevines throughout reproductive development. Leaf decreased throughout fruit development because water availability decreased towards the end of the reproductive cycle. CO₂ assimilation rate, leaf conductance and xylem ABA concentration also decreased during the course of the growing season. Combining all measurements xylem ABA was either not correlated, or only slightly correlated, with leaf water status + and daily leaf conductance, respectively. This lack of relationship indicates that xylem ABA during fruit ripening had functions other than provision of a non-hydraulic signal. On a seasonal basis, xylem ABA concentration measured in non-irrigated grapevines was well related to berry ABA concentration, especially at the end of fruit development (veraison and harvest).