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99 papers · 1 filter
On Finite Racks and Quandles
Pedro Lopes, Dennis Roseman
We revisit finite racks and quandles using a perspective based on permutations which can aid in the understanding of the structure. As a consequence we recover old results and prov…
Map Segmentation by Colour Cube Genetic K-Mean Clustering
Vitorino Ramos, Fernando Muge
Segmentation of a colour image composed of different kinds of texture regions can be a hard problem, namely to compute for an exact texture fields and a decision of the optimum num…
Global embedding of D-dimensional black holes with a cosmological constant in Minkowskian spacetimes: Matching between Hawking temperature and Unruh temperature
Nuno Loureiro Santos, Oscar J. C. Dias, José P. S. Lemos
We study the matching between the Hawking temperature of a large class of static D-dimensional black holes and the Unruh temperature of the corresponding higher dimensional Rindler…
Constant connections, quantum holonomies and the Goldman bracket
J. E. Nelson, R. F. Picken
In the context of (2+1)--dimensional quantum gravity with negative cosmological constant and topology R x T^2, constant matrix--valued connections generate a q--deformed representa…
Etale groupoids and their quantales
Pedro Resende
We establish a close and previously unknown relation between quantales and groupoids, in terms of which the notion of etale groupoid is subsumed in a natural way by that of quantal…
Transgression forms in dimension 4
Isabel M. C. Salavessa, Ana Pereira do Vale
We compute explicit transgression forms for the Euler and Pontrjagin classes of a Riemannian manifold of dimension 4 under a conformal change of the metric, or a change to a Ri…