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2007

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Articles 4411 - 4440 of 6758

Full-Text Articles in Physical Sciences and Mathematics

Cryptogram Decoding For Ocr Using Numerization Strings, Gary Huang, Erik Learned-Miller, Andrew Mccallum Jan 2007

Cryptogram Decoding For Ocr Using Numerization Strings, Gary Huang, Erik Learned-Miller, Andrew Mccallum

Andrew McCallum

OCR systems for printed documents typically require large numbers of font styles and character models to work well. When given an unseen font, performance degrades even in the absence of noise. In this paper, we perform OCR in an unsupervised fashion without using any character models by using a cryptogram decoding algorithm. We present results on real and artificial OCR data.

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Organizing The Oca: Learning Faceted Subjects From A Library Of Digital Books, David Mimno, Andrew Mccallum Jan 2007

Organizing The Oca: Learning Faceted Subjects From A Library Of Digital Books, David Mimno, Andrew Mccallum

Andrew McCallum

Large scale library digitization projects such as the Open Content Alliance are producing vast quantities of text, but little has been done to organize this data. Subject headings inherited from card catalogs are useful but limited, while full-text indexing is most appropriate for readers who already know exactly what they want. Statistical topic models provide a complementary function. These models can identify semantically coherent ``topics'' that are easily recognizable and meaningful to humans, but they have been too computationally intensive to run on library-scale corpora. This paper presents DCM-LDA, a topic model based on Dirichlet Compound Multinomial distributions. This model …

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Efficient Computation Of Entropy Gradient For Semi-Supervised Conditional Random Fields, Gideon S. Mann, Andrew Mccallum Jan 2007

Efficient Computation Of Entropy Gradient For Semi-Supervised Conditional Random Fields, Gideon S. Mann, Andrew Mccallum

Andrew McCallum

Entropy regularization is a straightforward and successful method of semi-supervised learning that augments the traditional conditional likelihood objective function with an additional term that aims to minimize the predicted label entropy on unlabeled data. It has previously been demonstrated to provide positive results in linear-chain CRFs, but the published method for calculating the entropy gradient requires significantly more computation than supervised CRF training. This paper presents a new derivation and dynamic program for calculating the entropy gradient that is significantly more efficient---having the same asymptotic time complexity as supervised CRF training. We also present efficient generalizations of this method for …

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Canonicalization Of Database Records Using Adaptive Similarity Measures, Aron Culotta, Michael Wick, Robert Hall, Matthew Marzilli, Andrew Mccallum Jan 2007

Canonicalization Of Database Records Using Adaptive Similarity Measures, Aron Culotta, Michael Wick, Robert Hall, Matthew Marzilli, Andrew Mccallum

Andrew McCallum

It is becoming increasingly common to construct databases from information automatically culled from many heterogeneous sources. For example, a research publication database can be constructed by automatically extracting titles, authors, and conference information from papers and their references. A common difficulty in consolidating data from multiple sources is that records are referenced in a variety of ways (e.g. abbreviations, aliases, and misspellings). Therefore, it can be difficult to construct a single, standard representation to present to the user. We refer to the task of constructing this representation as canonicalization. Despite its importance, there is very little existing work on canonicalization. …

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Improved Dynamic Schedules For Belief Propagation, Charles Sutton, Andrew Mccallum Jan 2007

Improved Dynamic Schedules For Belief Propagation, Charles Sutton, Andrew Mccallum

Andrew McCallum

Belief propagation and its variants are popular methods for approximate inference, but their running time and even their convergence depend greatly on the schedule used to send the messages. Recently, dynamic update schedules have been shown to converge much faster on hard networks than static schedules, namely the residual BP schedule of Elidan et al. [2006]. But that RBP algorithm wastes message updates: many messages are computed solely to determine their priority, and are never actually performed. In this paper, we show that estimating the residual, rather than calculating it directly, leads to significant decreases in the number of messages …

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The Impact Of Grey Literature In Advancing Global Karst Research: An Information Needs Assessment For A Globally Distributed Interdisciplinary Community, Todd A. Chavez, Anna H. Perrault, Pete Reehling, Courtney Crummett Jan 2007

The Impact Of Grey Literature In Advancing Global Karst Research: An Information Needs Assessment For A Globally Distributed Interdisciplinary Community, Todd A. Chavez, Anna H. Perrault, Pete Reehling, Courtney Crummett

Anna H. Perrault

A survey of the global karst community was conducted in 2006. The survey was distributed via the World Wide Web to known karst researchers. The instrument was designed to generate an initial inventory of core grey information types, to assess levels of usage of grey information by the respondents, and to gauge the karst community’s willingness to participate in building and expanding both this collection and the associated controlled vocabularies.

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Synthesis Of Trifluoromethyl-Imines By Solid Acid/Superacid Catalyzed Microwave-Assisted Approach, Abid Shaikh, Markku Savolainen, Shainaz M. Landge, Jinbo Hu, G. K. S. Prakash, George A. Olah, Béla Török Jan 2007

Synthesis Of Trifluoromethyl-Imines By Solid Acid/Superacid Catalyzed Microwave-Assisted Approach, Abid Shaikh, Markku Savolainen, Shainaz M. Landge, Jinbo Hu, G. K. S. Prakash, George A. Olah, Béla Török

Abid Shaikh

Trifluoromethyl, Imine, Clay, Solid acids, Solid superacid, Catalysis, Microwave irradiation Abstract: A new solid acid/superacid catalyzed microwave assisted synthesis of trifluoromethyl-imines is described. Various α,α,α-trifluoromethylketones react readily with primary amines to produce the corresponding imines. Two different strategies have been employed; one is the application of microwave irradiation coupled with solvent-free solid acid catalysis. The other method, for highly deactivated substrates includes the use of a pressure vessel at 175 °C temperature, with solid superacid catalysis. Using the solid acid K-10 montmorillonite or the superacidic perfluorinated resinsulfonic acid Nafion-H, a wide variety of trifluoromethylated imines have been synthesized using the …

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Learning Extractors From Unlabeled Text Using Relevant Databases, Kedar Bellare, Andrew Mccallum Jan 2007

Learning Extractors From Unlabeled Text Using Relevant Databases, Kedar Bellare, Andrew Mccallum

Andrew McCallum

Supervised machine learning algorithms for information extraction generally require large amounts of training data. In many cases where labeling training data is burdensome, there may, however, already exist an incomplete database relevant to the task at hand. Records from this database can be used to label text strings that express the same information. For tasks where text strings do not follow the same format or layout, and additionally may contain extra information, labeling the strings completely may be problematic. This paper presents a method for training extractors which fill in missing labels of a text sequence that is partially labeled …

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Nonparametric Bayes Pachinko Allocation, Wei Li, David Blei, Andrew Mccallum Jan 2007

Nonparametric Bayes Pachinko Allocation, Wei Li, David Blei, Andrew Mccallum

Andrew McCallum

Amherst, MA 01003 David Blei Computer Science Department Princeton University Princeton, NJ 08540 Andrew McCallum Department of Computer Science University of Massachusetts Amherst, MA 01003 Abstract Recent advances in topic models have explored complicated structured distributions to represent topic correlation. For example, the pachinko allocation model (PAM) captures arbitrary, nested, and possibly sparse correlations between topics using a directed acyclic graph (DAG). While PAM provides more flexibility and greater expressive power than previous models like latent Dirichlet allocation (LDA), it is also more difficult to determine the appropriate topic structure for a specific dataset. In this paper, we propose a …

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Leveraging Existing Resources Using Generalized Expectation Criteria, Gregory Druck, Gideon Mann, Andrew Mccallum Jan 2007

Leveraging Existing Resources Using Generalized Expectation Criteria, Gregory Druck, Gideon Mann, Andrew Mccallum

Andrew McCallum

It is difficult to apply machine learning to many real-world tasks because there are no existing labeled instances. In one solution to this problem, a human expert provides instance labels that are used in traditional supervised or semi-supervised training. Instead, we want a solution that allows us to leverage existing resources other than complete labeled instances. We propose the use of generalized expectation (GE) criteria to achieve this goal. A GE criterion is a term in a training objective function that assigns a score to values of a model expectation. In this paper, the expectations are model predicted class distributions …

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Undirected And Interpretable Continuous Topic Models Of Documents, X. Wang, K. Crammer, Andrew Mccallum Jan 2007

Undirected And Interpretable Continuous Topic Models Of Documents, X. Wang, K. Crammer, Andrew Mccallum

Andrew McCallum

We propose a new type of undirected graphical model suitable for topic modeling and dimensionality reduction for large text collections. Unlike previous Boltzmann machine and harmonium based methods, this new model represents words using Discrete distributions akin to traditional `bag-of-words' methods. However, in contrast to directed topic models such as latent Dirichlet allocation, each word is drawn from a distribution that takes into account all possible topics, as opposed to a topic-specific distribution. Furthermore, our models use positive continuous valued latent variables and learn more interpretable latent topic spaces than previous undirected techniques. As other undirected models, once such models …

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Author Disambiguation Using Error-Driven Machine Learning With A Ranking Loss Function, Aron Culotta, Pallika Kanani, Robert Hall, Michael Wick, Andrew Mccallum Jan 2007

Author Disambiguation Using Error-Driven Machine Learning With A Ranking Loss Function, Aron Culotta, Pallika Kanani, Robert Hall, Michael Wick, Andrew Mccallum

Andrew McCallum

Author disambiguation is the problem of determining whether records in a publications database that contain similar author names refer to the same person. This task can be especially difficult when the database is constructed from automatically extracted data, which can contain noisy and incomplete records. A common supervised machine learning approach to author disambiguation is to build a classifier that predicts whether a pair of records is coreferent, often followed by a collective inference step to enforce transitivity of the predictions. By restricting the classifier to pairwise predictions, standard training algorithms for binary classification can be used. However, this approach …

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On A Convex Operator For Finite Sets, Branko Ćurgus, Krzysztof Kołodziejczyk Jan 2007

On A Convex Operator For Finite Sets, Branko Ćurgus, Krzysztof Kołodziejczyk

Mathematics Faculty Publications

Let S be a finite set with m elements in a real linear space and let be a set of m intervals in . We introduce a convex operator which generalizes the familiar concepts of the convex hull, , and the affine hull, , of S . We prove that each homothet of that is contained in can be obtained using this operator. A variety of convex subsets of with interesting combinatorial properties can also be obtained. For example, this operator can assign a regular dodecagon to the 4-element set consisting of the vertices and the orthocenter of an equilateral …

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Ergodicity Conditions In A Simple Best Effort Queueing Networks, Abdeldjebbar Kandouci, Abdelmadjid Ezzine, Toufik Guendouzi Jan 2007

Ergodicity Conditions In A Simple Best Effort Queueing Networks, Abdeldjebbar Kandouci, Abdelmadjid Ezzine, Toufik Guendouzi

Turkish Journal of Mathematics

No abstract provided.

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Semi-Slant Submanifolds Of A Nearly Kaehler Manifold, Viqar Azam Khan, Meraj Ali Khan Jan 2007

Semi-Slant Submanifolds Of A Nearly Kaehler Manifold, Viqar Azam Khan, Meraj Ali Khan

Turkish Journal of Mathematics

The aim in the present paper is to study some basic geometric properties of semi-slant submanifolds of a nearly Kaehler manifold.

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On Cartan Spaces With (\Alpha, \Beta)-Metric, H. G. Nagaraja Jan 2007

On Cartan Spaces With (\Alpha, \Beta)-Metric, H. G. Nagaraja

Turkish Journal of Mathematics

É. Cartan [2] has originally introduced a Cartan space, which is considered as dual of Finsler space. H. Rund [10], F. Brickell [1] and others studied the relation between these two spaces. The theory of Hamilton spaces was introduced and studied by R. Miron ([8 , [9]). He proved that Cartan space is a particular case of Hamilton space. T. Igrashi ([5], [6]) introduced the notion of the (\alpha, \beta)-metric in Cartan spaces and obtained the metric tensor and the invariants \rho and r which characterize the special classes of Cartan spaces with (\alpha, \beta)-metric. This paper presents a study …

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On Graded Secondary Modules, Shahabaddin Ebrahimi Atani, F. Farzalipour Jan 2007

On Graded Secondary Modules, Shahabaddin Ebrahimi Atani, F. Farzalipour

Turkish Journal of Mathematics

Let G be a group with identity e, and let R be a G-graded commutative ring. Here we study the graded primary submodules of a G-graded R-module and examine when graded submodules of a graded representable module are graded representable. A number of results concerning of these class of submodules are given.

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The Compact Metric Space Of The Lattice Of Varieties And ^{*}-Varieties Of C^{*}-Algebras, G. Khalilzadeh, Mohammad Hasan Faroughi Jan 2007

The Compact Metric Space Of The Lattice Of Varieties And ^{*}-Varieties Of C^{*}-Algebras, G. Khalilzadeh, Mohammad Hasan Faroughi

Turkish Journal of Mathematics

Variety of Banach algebras is a non-empty class of Banach algebras in which there exist a family of laws such that all of its members satisfy all of the laws. In this paper, we have used merely mathematical items such as Banach algebras and varieties including Banach algebras in order to change the space of all varieties of Banach algebras into a compact metric space. We prove some theorems in the metric space of zero at infinity varieties, define the ^*-varieties of ^{*}-algebra and prove many theorems about ^*-varieties of C^*-algebras.

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Equilibria In A Dipersal Model For Structured Populations, Maref Y. M. Alzoubi Jan 2007

Equilibria In A Dipersal Model For Structured Populations, Maref Y. M. Alzoubi

Turkish Journal of Mathematics

We derive a model for structured population with a two-phase life cycle. Growth and reproduction occur during the first phase. The first phase is followed by a dispersal phase in which individuals are allowed to move throughout a habitat. Also, we prove the existence of a branch of positive equilibria using bifurcation results of Rabinowitz.

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On Nuclearity Of Köthe Spaces, Erdal Karapinar, V. Zakharyuta Jan 2007

On Nuclearity Of Köthe Spaces, Erdal Karapinar, V. Zakharyuta

Turkish Journal of Mathematics

In this study we observe that the Köthe space K^{l_p}(A) is nuclear if it is isomorphic to a complemented subspace of K^{l_q}(B) for 1\leq p < q < \infty and p < 2.

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Induced Mappings On Boolean Algebras Of Clopen Sets And On Projections Of The C^*-Algebra C(X), Ahmed Al-Rawashdeh, Wasfi Shatanawi Jan 2007

Induced Mappings On Boolean Algebras Of Clopen Sets And On Projections Of The C^*-Algebra C(X), Ahmed Al-Rawashdeh, Wasfi Shatanawi

Turkish Journal of Mathematics

For a compact space X, any group automorphism \varphi of C(X,S^1) induces a mapping \Theta on the Boolean algebra of the clopen subsets of X. We prove that the disjointness of \Theta equivalent to \theta_{\varphi} is an orthoisomorphism on the sets of projections of the C^*-algebra C(X), when \varphi(-1)=-1. Indeed, \Theta is a Boolean isomorphism iff \theta_{\varphi} preserves the product of projections. If X is equipped with a probability measure \mu, on a certain \sigma-algebra of X, we show (under some condition) that \Theta preserves the disjoint of clopen subsets, up to sets of measure zero, or equivalently, the mapping …

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Some Remarks On The L^P - L^Q Boundedness Of Uc_{\Varphi}, M. R. Jabbarzadeh Jan 2007

Some Remarks On The L^P - L^Q Boundedness Of Uc_{\Varphi}, M. R. Jabbarzadeh

Turkish Journal of Mathematics

In this paper we will consider the weighted composition operators between two different L^p-spaces and then we characterize the functions u and transformations \varphi that induce weighted composition operator uC_{\varphi} between L^p(X, \Sigma, \mu)-spaces by using some properties of conditional expectation operator, pair (u, \varphi) and the measure space (X, \Sigma, \mu).

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Braiding For Categorical And Crossed Lie Algebras And Simplicial Lie Algebras, Erdal Ulualan Jan 2007

Braiding For Categorical And Crossed Lie Algebras And Simplicial Lie Algebras, Erdal Ulualan

Turkish Journal of Mathematics

In this work, we give the notion of braiding for categorical Lie algebras and crossed modules of Lie algebras and we give an equivalence between them.

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On The Unique Continuation Property For The Higher Order Nonlinear Schrödinger Equation With Constant Coefficients, Vanilde Bisognin, Octavio Paulo Vera Villagran Jan 2007

On The Unique Continuation Property For The Higher Order Nonlinear Schrödinger Equation With Constant Coefficients, Vanilde Bisognin, Octavio Paulo Vera Villagran

Turkish Journal of Mathematics

We solve the unique continuation property: If u is a solution of the higher order nonlinear Schrödinger equation with constant coefficients with t_1 < t_2 which is sufficiently smooth and such that supp u( . , t_j) \subset (a, b), -\infty < a < b < \infty, j = 1, 2, then u \equiv 0.

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Real Aspects Of The Moduli Space Of Genus Zero Stable Maps, Seongchun Kwon Jan 2007

Real Aspects Of The Moduli Space Of Genus Zero Stable Maps, Seongchun Kwon

Turkish Journal of Mathematics

We show that the moduli space of genus zero stable maps is a real projective variety if the target space is a smooth convex real projective variety. We show that evaluation maps, forgetful maps are real morphisms. We analyze the real part of the moduli space.

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Steepness In Natural Exponential Families, Afif Masmoudi Jan 2007

Steepness In Natural Exponential Families, Afif Masmoudi

Turkish Journal of Mathematics

The present paper studies and develops the notion of steepness in multivariate natural exponential families. Let F = \{P(m,F); m \in M_F\} be a multidimensional natural exponential family parameterized by its domain of the means M_F and let \overline{m} be an element of \partial M_F the means domain boundary. A necessary and sufficient condition for the variance function V_F is established so that the family F be steep at \overline{m} \in \partial M_F. Some characteristic properties of a steep family are given. Also, we investigate the asymptotic behaviour of a steep family F at \overline{m}.

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Multipliers And The Relative Completion In L_W^P(G), Cenap Duyar, A. Turan Gürkanli Jan 2007

Multipliers And The Relative Completion In L_W^P(G), Cenap Duyar, A. Turan Gürkanli

Turkish Journal of Mathematics

Quek and Yap defined a relative completion à for a linear subspace A of L^p(G), 1 \leq p < \infty ; and proved that there is an isometric isomorphism, between Hom_{L^1(G)}(L^1(G), A) and Ã, where Hom_{L^1(G)}(L^1(G),A) is the space of the module homomorphisms (or multipliers) from L^1(G) to A. In the present, we defined a relative completion à for a linear subspace A of L_w^p(G) ,where w is a Beurling's weighted function and L_w^p(G) is the weighted L^p(G) space, ([14]). Also, we proved that there is an algeabric isomorphism and homeomorphism, between Hom_{L_w^1(G)} (L_w^1(G),A) and Ã. At the end of this work we gave some applications and examples.

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The Construction Of Maximum Independent Set Of Matrices Via Clifford Algebras, Nedi̇m Deği̇rmenci̇, Nüli̇fer Özdemi̇r Jan 2007

The Construction Of Maximum Independent Set Of Matrices Via Clifford Algebras, Nedi̇m Deği̇rmenci̇, Nüli̇fer Özdemi̇r

Turkish Journal of Mathematics

In [1], [2] and [6] the maximum number of some special type n x n matrices with elements in F whose nontrivial linear combinations with real coefficients are nonsingular is studied where F is the real field R, the complex field C or the skew field H of quaternions. In this work we construct such matrices explicitly by using representations of Clifford algebras. At the end we give some analogues of the celebrated theorem of Radon-Hurwitz.

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On The Normalizer Of The Congruence Subgroup H_0^5(I) Of The Hecke Group H^5, Süleyman Uzun Jan 2007

On The Normalizer Of The Congruence Subgroup H_0^5(I) Of The Hecke Group H^5, Süleyman Uzun

Turkish Journal of Mathematics

Let l = 2 cos \frac{\pi}{5} and let H^5 be the Hecke group associated to l. In this paper, the normalizers of the congruence subgroups H_0^5(I) in PSL(2Z[\lambda]) are studied in the case where I = (2)^aI ', (2, I') = 1 and I' is a prime ideal.

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An Investigation On A Subclass Of P-Valently Starlike Functions In The Unit Disc, Yaşar Polatoğlu, Meti̇n Bolcal, Arzu Şen, Emel Yavuz Duman Jan 2007

An Investigation On A Subclass Of P-Valently Starlike Functions In The Unit Disc, Yaşar Polatoğlu, Meti̇n Bolcal, Arzu Şen, Emel Yavuz Duman

Turkish Journal of Mathematics

Let A_p denote the class of functions of the form f(z) = z^p+a_{p+1}z^{p+1}+a_{p+2}z^{p+2}+ ··· which are regular and p-valent in the open unit disc D = {z : z < 1}. Let M_p(\alpha) be the subclass of A_p consisting of functions f(z) which satisfy Re ( z \frac{f'(z)}{f(z)}) < \alpha, (z \in D) for some real \alpha (\alpha > 1). The aim of this paper is to give a representation theorem, a distortion theorem and a coefficient inequality for the class M_p(\alpha).

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