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Search Results: 1 - 10 of 133 matches for " Zur Izhakian "
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Tropical Algebraic Sets, Ideals and An Algebraic Nullstellensatz
Zur Izhakian
Mathematics , 2005,
Abstract: This paper introduces the foundations of the polynomial algebra and basic structures for algebraic geometry over the extended tropical semiring. Our development, which includes the tropical version for the fundamental theorem of algebra, leads to the reduced polynomial semiring -- a structure that provides a basis for developing a tropical analogue to the classical theory of commutative algebra. The use of the new notion of tropical algebraic com-sets, built upon the complements of tropical algebraic sets, eventually yields the tropical algebraic Nullstellensatz.
The Tropical Rank of a Tropical Matrix
Zur Izhakian
Mathematics , 2006,
Abstract: In this paper we further develop the theory of matrices over the extended tropical semiring. Introducing a notion of tropical linear dependence allows for a natural definition of matrix rank in a sense that coincides with the notions of tropical regularity and invertibility.
Duality of Tropical Curves
Zur Izhakian
Mathematics , 2005,
Abstract: Duality of curves is one of the important aspects of the ``classical'' algebraic geometry. In this paper, using this foundation, the duality of tropical polynomials is constructed to introduce the duality of Non-Archimedean curves. Using the development of ``mechanism'' which is based on ``distortion'' values and their matrices, we discuss some aspects refereing to quadrics with respect to their dual objects. This topic includes also the induced dual subdivision of Newton Polytope and its compatible properties. Finally, a regularity of tropical curves in the duality sense is generally defined and, studied for families of tropical quadrics.
Tropical Arithmetic and Tropical Matrix Algebra
Zur Izhakian
Mathematics , 2005,
Abstract: This paper introduces a new structure of commutative semiring, generalizing the tropical semiring, and having an arithmetic that modifies the standard tropical operations, i.e. summation and maximum. Although our framework is combinatorial, notions of regularity and invertibility arise naturally for matrices over this semiring; we show that a tropical matrix is invertible if and only if it is regular.
Semigroup identities in the monoid of triangular tropical matrices
Zur Izhakian
Mathematics , 2013,
Abstract: We show that the submonoid of all nxn triangular tropical matrices satisfies a nontrivial semigroup identity and provide a generic construction for classes of such identities. The utilization of the Fibonacci number formula gives us an upper bound on the length of these 2-variable semigroup identities.
Algebraic Curves in Parallel Coordinates - Avoiding the "Over-Plotting" Problem
Zur Izhakian
Computer Science , 2004,
Abstract: ${\cal U}$ntil now the representation (i.e. plotting) of curve in Parallel Coordinates is constructed from the point $\leftrightarrow$ line duality. The result is a ``line-curve'' which is seen as the envelope of it's tangents. Usually this gives an unclear image and is at the heart of the ``over-plotting'' problem; a barrier in the effective use of Parallel Coordinates. This problem is overcome by a transformation which provides directly the ``point-curve'' representation of a curve. Earlier this was applied to conics and their generalizations. Here the representation, also called dual, is extended to all planar algebraic curves. Specifically, it is shown that the dual of an algebraic curve of degree $n$ is an algebraic of degree at most $n(n - 1)$ in the absence of singular points. The result that conics map into conics follows as an easy special case. An algorithm, based on algebraic geometry using resultants and homogeneous polynomials, is obtained which constructs the dual image of the curve. This approach has potential generalizations to multi-dimensional algebraic surfaces and their approximation. The ``trade-off'' price then for obtaining {\em planar} representation of multidimensional algebraic curves and hyper-surfaces is the higher degree of the image's boundary which is also an algebraic curve in $\|$-coords.
New Visualization of Surfaces in Parallel Coordinates - Eliminating Ambiguity and Some "Over-Plotting"
Zur Izhakian
Computer Science , 2004,
Abstract: $\cal{A}$ point $P \in \Real^n$ is represented in Parallel Coordinates by a polygonal line $\bar{P}$ (see \cite{Insel99a} for a recent survey). Earlier \cite{inselberg85plane}, a surface $\sigma$ was represented as the {\em envelope} of the polygonal lines representing it's points. This is ambiguous in the sense that {\em different} surfaces can provide the {\em same} envelopes. Here the ambiguity is eliminated by considering the surface $\sigma$ as the envelope of it's {\em tangent planes} and in turn, representing each of these planes by $n$-1 points \cite{Insel99a}. This, with some future extension, can yield a new and unambiguous representation, $\bar{\sigma}$, of the surface consisting of $n$-1 planar regions whose properties correspond lead to the {\em recognition} of the surfaces' properties i.e. developable, ruled etc. \cite{hung92smooth}) and {\em classification} criteria. It is further shown that the image (i.e. representation) of an algebraic surface of degree 2 in $\Real^n$ is a region whose boundary is also an algebraic curve of degree 2. This includes some {\em non-convex} surfaces which with the previous ambiguous representation could not be treated. An efficient construction algorithm for the representation of the quadratic surfaces (given either by {\em explicit} or {\em implicit} equation) is provided. The results obtained are suitable for applications, to be presented in a future paper, and in particular for the approximation of complex surfaces based on their {\em planar} images. An additional benefit is the elimination of the ``over-plotting'' problem i.e. the ``bunching'' of polygonal lines which often obscure part of the parallel-coordinate display.
Phantom Probability
Yehuda Izhakian,Zur Izhakian
Mathematics , 2009,
Abstract: Classical probability theory supports probability measures, assigning a fixed positive real value to each event, these measures are far from satisfactory in formulating real-life occurrences. The main innovation of this paper is the introduction of a new probability measure, enabling varying probabilities that are recorded by ring elements to be assigned to events; this measure still provides a Bayesian model, resembling the classical probability model. By introducing two principles for the possible variation of a probability (also known as uncertainty, ambiguity, or imprecise probability), together with the "correct" algebraic structure allowing the framing of these principles, we present the foundations for the theory of phantom probability, generalizing classical probability theory in a natural way. This generalization preserves many of the well-known properties, as well as familiar distribution functions, of classical probability theory: moments, covariance, moment generating functions, the law of large numbers, and the central limit theorem are just a few of the instances demonstrating the concept of phantom probability theory.
Supertropical matrix algebra III: Powers of matrices and generalized eigenspaces
Zur Izhakian,Louis Rowen
Mathematics , 2010,
Abstract: We investigate powers of supertropical matrices, with special attention to the role of the coefficients of the supertropical characteristic polynomial (especially the supertropical trace) in controlling the rank of a power of a matrix. This leads to a Jordan-type decomposition of supertropical matrices, together with a generalized eigenspace decomposition of a power of an arbitrary supertropical matrix.
New Representations of Matroids and Generalizations
Zur Izhakian,John Rhodes
Mathematics , 2011,
Abstract: We extend the notion of matroid representations by matrices over fields and consider new representations of matroids by matrices over finite semirings, more precisely over the boolean and the superboolean semirings. This idea of representations is generalized naturally to include also hereditary collections. We show that a matroid that can be directly decomposed as matroids, each of which is representable over a field, has a boolean representation, and more generally that any arbitrary hereditary collection is superboolean-representable.
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