منابع مشابه
Computing Surfaces via pq-Permutations
In algebraic topology, compact 2-dimensional manifolds are usually dealt through a well-defined class of words denoting polygonal presentations. In this paper, we show how to eliminate the useless bureaucracy intrinsic to word-based presentations by considering very simple combinatorial structures called pq-permutations. Thanks to their effectiveness, pq-permutations allow to define a rewriting...
متن کاملPlanarity Algorithms via PQ-Trees
We give a linear-time planarity test that unifies and simplifies the algorithms of Shih and Hsu and Boyer and Myrvold; in our view, these algorithms are really one algorithm with different implementations. This leads to a short and direct proof of correctness without the use of Kuratowski’s theorem. Our planarity test extends to give a uniform random embedding, to count embeddings, to represent...
متن کاملComputing signed permutations of polygons
Given a planar polygon (or chain) with a list of edges {e1, e2, e3, . . . , en−1, en}, we examine the effect of several operations that permute this edge list, resulting in the formation of a new polygon. The main operations that we consider are: reversals which involve inverting the order of a sublist, transpositions which involve interchanging subchains (sublists), and edge-swaps which are a ...
متن کاملPermutations via linear translators
We show that many infinite classes of permutations over finite fields can be constructed via translators with a large choice of parameters. We first characterize some functions having linear translators, based on which several families of permutations are then derived. Extending the results of [9], we give in several cases the compositional inverse of these permutations. The connection with com...
متن کاملTopological Classification of Conformal Actions on pq-Hyperelliptic Riemann Surfaces
A compact Riemann surface X of genus g > 1 is said to be p-hyperelliptic if X admits a conformal involution ρ for which X/ρ is an orbifold of genus p. Here we classify conformal actions on 2-hyperelliptic Rieman surfaces of genus g > 9, up to topological conjugacy and determine which of them can be maximal.
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ژورنال
عنوان ژورنال: International Journal of Imaging Systems and Technology
سال: 2009
ISSN: 0899-9457,1098-1098
DOI: 10.1002/ima.20186