We prove that the art gallery problem is equivalent under polynomial time reductions to deciding whether a system of polynomial equations over the real numbers has a solution. The art gallery problem is a classical problem in computational geometry, introduced in 1973 by Victor Klee. Given a simple polygon P and an integer k, the goal is to decide if there exists a set G of k guards within P su...

Consider an art gallery formed by a polygon on n vertices with m pairs of vertices joined by interior diagonals, the interior walls. Each interior wall has an arbitrarily placed, arbitrarily small doorway. We will show that the minimum number of guards that suffice to guard all art galleries with n vertices and m interior walls is min{b(2n−3)/3c, b(2n+m−2)/4c, b(2m+n)/3c}. If we restrict oursel...

Cracids are generalist frugivores, which often exploit plant food resources such as flowers and leaves, mainly when fruit production declines. The Chaco chachalaca (Ortalis canicollis) is the most abundant cracid in the Pantanal (Brazil), and particularly common in the gallery forests. However, the factors related to their occurrence in this habitat type are unclear. In this study I describe th...

BACKGROUND Knowledge on synanthropic phlebotomines and their natural infection by Leishmania is necessary for the identification of potential areas for leishmaniasis occurrence. OBJECTIVE To analyse the occurrence of Phlebotominae in gallery forests and household units (HUs) in the city of Palmas and to determine the rate of natural infection by trypanosomatids. METHODS Gallery forests and ...

Kew Gardens in London opened last month the first gallery in the world to open all year round dedicated to botanical illustrations. The gallery will showcase art from Kew’s unique historic collections as well as Shirley Sherwood’s contemporary collection of botanical art. The two collections, which complement each other, will allow Kew to show to the public many of its largely unseen works and ...

Parakeets usually forage for massive and ephemeral plant resources at forest canopies. Fruit pulp is widely cited as a major food resource for these birds, which often eat seeds and nectar. In this study, I assessed flower and fruit production at a gallery forest in the Pantanal flood plain (Brazil) in order to evaluate the relationship between food resource production and abundance of a common...

In 1973, Victor Klee posed the problem of determining the minimum number of guards sufficient to cover the interior of an n-wall art gallery room (Honsberger 1976). He posed this question extemporaneously in response to a request from Vasek Chvatal (at a conference at Stanford in August) for an interesting geometric problem, and Chvatal soon established what has become known as "Chvatal's Art G...

Spherical and cylindrical dielectric cavities support high Q whispering gallery modes due to total internal reflection of the trapped light. When such a cavity is deformed smoothly the ray dynamics of these modes becomes chaotic in a manner determined by the KAM theory of classical hamiltonian dynamics. The universal properties of the ray dynamics predicted by KAM theory allow a general underst...

In December 1998 the National Gallery of Art, Washington DC, working with Cognitive Applications of Brighton, England, published The National Gallery of Art Washington CD-ROM. This publication is the latest generation in the famiiy line that began at the National Gallery i n London when the original Micro Gallery, conceived way back in 1987, was delivered in July 1991. Each generation of this f...

According to the Convention on Biological Diversity (CBD) the development of bioindicators is extremely necessary to achieve the conservation targets by 2010, and insects are considered an effective group for this goal. Drosophilids are regarded as potential indicators, although this idea remains untested. Therefore, we followed up a protocol to test the drosophilid potential indicator for huma...