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- Instituto Politécnico de LisboaPT10 papers
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12 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…
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…
Quantum Walk on a Line with Two Entangled Particles
Y. Omar, N. Paunkovic, L. Sheridan +1
We introduce the concept of a quantum walk with two particles and study it for the case of a discrete time walk on a line. A quantum walk with more than one particle may contain en…