منابع مشابه
A1-contractibility and topological contractibility
These notes are an extended transcript of two lectures given at the University of Ottawa during the workshop “Group actions, generalized cohomology theories, and affine algebraic geometry." The first lecture was a general introduction to A1-homotopy theory focusing on motivating the choice of definitions in the construction, together with a definition of A1-contractible spaces. The second lectu...
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For a fixed graph H, let H-CON denote the problem of determining whether a given graph is contractible to H. The complexity of H-CON is studied for H belonging to certain classes of graphs, together covering all connected graphs of order at most 4. In particular, H-CON is NP-complete if H is a connected triangle-free graph other than a star. For each connected graph H of order a t most 4 other ...
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Consider the following relaxation of the Hadwiger Conjecture: For each t there exists Nt such that every graph with no Kt minor admits a vertex partition into dαt + βe parts, such that each component of the subgraph induced by each part has at most Nt vertices. The Hadwiger Conjecture corresponds to the case α = 1, β = −1 and Nt = 1. Kawarabayashi and Mohar [K. Kawarabayashi, B. Mohar, A relaxe...
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This paper examines the determinants of intra-firm trade in US imports using detailed country-product data. We create a new measure of product contractibility based on the degree of intermediation in international trade for the product. We find important roles for the interaction of country and product characteristics in determining intra-firm trade shares. Intra-firm trade is high for products...
متن کاملSelections
It was not until the sixteenth century that dead bodies were submitted to medico-legal investigation. The horror which human dissections inspired in the ancients, and the religious awe with which they beheld the mortal wreck of their fellows, not only retarded the progress of anatomy and physiology, but excluded the light of medicine from the researches of the forum. The Jewish law, indeed, con...
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ژورنال
عنوان ژورنال: Fundamenta Mathematicae
سال: 1980
ISSN: 0016-2736,1730-6329
DOI: 10.4064/fm-108-2-109-118