Low rank subspace clustering (LRSC)

We consider the problem of fitting a union of subspaces to a collection of data points drawn from one or more subspaces and corrupted by noise and/or gross errors. We pose this problem as a non-convex optimization problem, where the goal is to decompose the corrupted data matrix as the sum of a clean and self-expressive dictionary plus a matrix of noise and/or gross errors. By self-expressive we mean a dictionary whose atoms can be expressed as linear combinations of themselves with low-rank coefficients. In the case of noisy data, our key contribution is to show that this non-convex matrix decomposition problem can be solved in closed form from the SVD of the noisy data matrix. The solution involves a novel polynomial thresholding operator on the singular values of the data matrix, which requires minimal shrinkage. For one subspace, a particular case of our framework leads to classical PCA, which requires no shrinkage. For multiple subspaces, the low-rank coefficients obtained by our framework can be used to construct a data affinity matrix from which the clustering of the data according to the subspaces can be obtained by spectral clustering. In the case of data corrupted by gross errors, we solve the problem using an alternating minimization approach, which combines our polynomial thresholding operator with the more traditional shrinkage-thresholding operator. Experiments on motion segmentation and face clustering show that our framework performs on par with state-of-the-art techniques at a reduced computational cost.

Twenty questions with noise: Bayes optimal policies for entropy loss

We consider the problem of twenty questions with noisy answers, in which we seek to find a target by repeatedly choosing a set, asking an oracle whether the target lies in this set, and obtaining an answer corrupted by noise. Starting with a prior distribution on the target's location, we seek to minimize the expected entropy of the posterior distribution. We formulate this problem as a dynamic program and show that any policy optimizing the one-step expected reduction in entropy is also optimal over the full horizon. Two such Bayes optimal policies are presented: one generalizes the probabilistic bisection policy due to Horstein and the other asks a deterministic set of questions. We study the structural properties of the latter, and illustrate its use in a computer vision application.

O influxo da dialética humanista e a reforma da teoria escolástica dos tópicos no Tractatus de locis dialecticis de Alonso de Veracruz

En el Tractatus de locis dialecticis, Alonso de la Veracruz (1507-1584) promueve una reforma de la teoría de los tópicos que se caracteriza por la combinación de algunos de los elementos más expresivos de tradiciones rivales y aparentemente antagónicas como es el caso de la dialéctica humanista y de la lógica escolástica. Para determinar si tales elementos estarían articulados de manera integrada y coherente en la teoría propuesta por Fray Alonso, evaluamos la compatibilidad entre las definiciones escolástica y agricoliana de tópico, visto que ambas igualmente fueron asimiladas por el Tractatus de locis dialecticis. En el estudio aquí presentado, defendemos que Alonso de la Veracruz concilia tales definiciones, concibiendo los tópicos bajo una perspectiva prioritariamente epistémica. En seguida, averiguamos lo que llevó a Fray Alonso a enaltecer las innovaciones de la dialéctica humanista y, al mismo tiempo, insistir en el uso de las proposiciones máximas, ignorando diversas críticas a ellas dirigidas por Rodolfo Agrícola. Acreditamos que tal dificultad puede ser dilucidada mediante la hipótesis de que Alonso de la Veracruz habría optado por el mantenimiento de las máximas en razón del importante papel por ellas ejercido en la fundamentación de las inferencias entimemáticas. Finalmente, investigamos las razones por las cuales la taxonomía alonsina de los tópicos no es inviabilizada por la presencia de trazos de las teorías escolástica y humanista de los tópicos. En ese contexto, asumimos que la clasificación de los tópicos sustentada por Fray Alonso no es corrompida por su carácter híbrido, una vez que ella compatibilizaría las doctrinas más relevantes de las tradiciones escolástica y humanista.

La creación del espacio trágico en la obra de Gabriel García Márquez : Una lectura sofoclea

La influencia de Sófocles y, concretamente, de las tragedias tebanas en la obra de García Márquez se manifiesta a niveles diversos: en la construcción de la trama, en la elaboración del personaje tiránico, en los temas de la violencia y el destino y, por supuesto, en el tratamiento del tiempo y del espacio. En este artículo se analiza la creación del espacio en García Márquez a través de dos elementos contrapuestos que provienen de su lectura de la tragedia sofoclea: el genos, símbolo de un espacio cerrado y ligado a un tiempo "redondo", el espacio del relato, y la polis, un lugar abierto y lejano, donde se produce la Historia con mayúsculas. Esta dicotomía será observada en distintas obras de García Márquez, pero especialmente en Edipo Alcalde. El conflicto trágico de la discordia civil se refleja, así pues, en la construcción de un espacio único, claustrofóbico y corrompido

La creación del espacio trágico en la obra de Gabriel García Márquez : Una lectura sofoclea

La influencia de Sófocles y, concretamente, de las tragedias tebanas en la obra de García Márquez se manifiesta a niveles diversos: en la construcción de la trama, en la elaboración del personaje tiránico, en los temas de la violencia y el destino y, por supuesto, en el tratamiento del tiempo y del espacio. En este artículo se analiza la creación del espacio en García Márquez a través de dos elementos contrapuestos que provienen de su lectura de la tragedia sofoclea: el genos, símbolo de un espacio cerrado y ligado a un tiempo "redondo", el espacio del relato, y la polis, un lugar abierto y lejano, donde se produce la Historia con mayúsculas. Esta dicotomía será observada en distintas obras de García Márquez, pero especialmente en Edipo Alcalde. El conflicto trágico de la discordia civil se refleja, así pues, en la construcción de un espacio único, claustrofóbico y corrompido

La creación del espacio trágico en la obra de Gabriel García Márquez : Una lectura sofoclea

La influencia de Sófocles y, concretamente, de las tragedias tebanas en la obra de García Márquez se manifiesta a niveles diversos: en la construcción de la trama, en la elaboración del personaje tiránico, en los temas de la violencia y el destino y, por supuesto, en el tratamiento del tiempo y del espacio. En este artículo se analiza la creación del espacio en García Márquez a través de dos elementos contrapuestos que provienen de su lectura de la tragedia sofoclea: el genos, símbolo de un espacio cerrado y ligado a un tiempo "redondo", el espacio del relato, y la polis, un lugar abierto y lejano, donde se produce la Historia con mayúsculas. Esta dicotomía será observada en distintas obras de García Márquez, pero especialmente en Edipo Alcalde. El conflicto trágico de la discordia civil se refleja, así pues, en la construcción de un espacio único, claustrofóbico y corrompido

Novel method to improve the signal-to-noise ratio in the far-field results obtained from planar near-field measurements

A method to reduce the noise power in far-field pattern without modifying the desired signal is proposed. Therefore, an important signal-to-noise ratio improvement may be achieved. The method is used when the antenna measurement is performed in planar near-field, where the recorded data are assumed to be corrupted with white Gaussian and space-stationary noise, because of the receiver additive noise. Back-propagating the measured field from the scan plane to the antenna under test (AUT) plane, the noise remains white Gaussian and space-stationary, whereas the desired field is theoretically concentrated in the aperture antenna. Thanks to this fact, a spatial filtering may be applied, cancelling the field which is located out of the AUT dimensions and which is only composed by noise. Next, a planar field to far-field transformation is carried out, achieving a great improvement compared to the pattern obtained directly from the measurement. To verify the effectiveness of the method, two examples will be presented using both simulated and measured near-field data.

Methods for noise reduction in far-field patterns obtained from cylindrical near-field antenna measurements

Two different methods to reduce the noise power in the far-field pattern of an antenna as measured in cylindrical near-field (CNF) are proposed. Both methods are based on the same principle: the data recorded in the CNF measurement, assumed to be corrupted by white Gaussian and space-stationary noise, are transformed into a new domain where it is possible to filter out a portion of noise. Those filtered data are then used to calculate a far-field pattern with less noise power than that one obtained from the measured data without applying any filtering. Statistical analyses are carried out to deduce the expressions of the signal-to-noise ratio improvement achieved with each method. Although the idea of the two alternatives is the same, there are important differences between them. The first one applies a modal filtering, requires an oversampling and improves the far-field pattern in all directions. The second method employs a spatial filtering on the antenna plane, does not require oversampling and the far-field pattern is only improved in the forward hemisphere. Several examples are presented using both simulated and measured near-field data to verify the effectiveness of the methods.

Image analysis by moment invariants using a set of step-like basis functions

Moment invariants have been thoroughly studied and repeatedly proposed as one of the most powerful tools for 2D shape identification. In this paper a set of such descriptors is proposed, being the basis functions discontinuous in a finite number of points. The goal of using discontinuous functions is to avoid the Gibbs phenomenon, and therefore to yield a better approximation capability for discontinuous signals, as images. Moreover, the proposed set of moments allows the definition of rotation invariants, being this the other main design concern. Translation and scale invariance are achieved by means of standard image normalization. Tests are conducted to evaluate the behavior of these descriptors in noisy environments, where images are corrupted with Gaussian noise up to different SNR values. Results are compared to those obtained using Zernike moments, showing that the proposed descriptor has the same performance in image retrieval tasks in noisy environments, but demanding much less computational power for every stage in the query chain.

Joint 4-D variational stereo reconstruction and camera calibration refinement for oceanic sea state measurements

Validating modern oceanographic theories using models produced through stereo computer vision principles has recently emerged. Space-time (4-D) models of the ocean surface may be generated by stacking a series of 3-D reconstructions independently generated for each time instant or, in a more robust manner, by simultaneously processing several snapshots coherently in a true ?4-D reconstruction.? However, the accuracy of these computer-vision-generated models is subject to the estimations of camera parameters, which may be corrupted under the influence of natural factors such as wind and vibrations. Therefore, removing the unpredictable errors of the camera parameters is necessary for an accurate reconstruction. In this paper, we propose a novel algorithm that can jointly perform a 4-D reconstruction as well as correct the camera parameter errors introduced by external factors. The technique is founded upon variational optimization methods to benefit from their numerous advantages: continuity of the estimated surface in space and time, robustness, and accuracy. The performance of the proposed algorithm is tested using synthetic data produced through computer graphics techniques, based on which the errors of the camera parameters arising from natural factors can be simulated.

Estimating risks in declining populations with poor data

Census data on endangered species are often sparse, error-ridden, and confined to only a segment of the population. Estimating trends and extinction risks using this type of data presents numerous difficulties. In particular, the estimate of the variation in year-to-year transitions in population size (the “process error” caused by stochasticity in survivorship and fecundities) is confounded by the addition of high sampling error variation. In addition, the year-to-year variability in the segment of the population that is sampled may be quite different from the population variability that one is trying to estimate. The combined effect of severe sampling error and age- or stage-specific counts leads to severe biases in estimates of population-level parameters. I present an estimation method that circumvents the problem of age- or stage-specific counts and is markedly robust to severe sampling error. This method allows the estimation of environmental variation and population trends for extinction-risk analyses using corrupted census counts—a common type of data for endangered species that has hitherto been relatively unusable for these analyses.

Misleaders of labor,

A corrupted labor leadership.--Class collaboration.--Reactionary labor politics.--Bribery and betrayal in various industries.--Organized graft in the building trades.--Plundering the workers.Trade union capitalism swindle.--Tainted labor journalism.--Autocratic control of the unions.--What must be done.

The works of William Shakespeare : the plays edited from the folio of MDCXXIII, with various readings from all the editions and all the commentators, notes, introductory remarks, a historical sketch of the text, an account of the rise and progress of the English drama, a memoir of the poet, and an essay upon his genius /

Publisher's advertisement (12 p.) at beginning of v. 2.

The writings of Mark Twain [pseud.]

Each vol. has general half-title and special t.-p.

The complete works of Mark Twain.

v.1. The adventures of Tom Sawyer -- v.2. The innocents abroad -- v.3. Pudd'nhead Wilson -- v.4. The America claimant -- v.5. A Connecticut Yankee in King Arthur's court -- v.6. Roughing it -- v.7. Life on the Mississippi -- v.8. The mysterious stranger -- v.9. The adventures of Huckleberry Finn -- v.10. The gilded age -- v.11. A tramp abroad -- v.12. What is man? -- v.13. Following the equator -- v.14. Tom Sawyer abroad -- v.15. The man that corrupted Hadleyburg -- v.16. In defense of Harriet Shelley -- v.17. Joan of Arc -- v.18. The $30,000 bequest -- v.19. Sketches old and new -- v.20. Europe and elsewhere -- v.21. The prince and the pauper -- v.22. Mark Twain's notebook -- v.23. Christian science -- v.24. Mark Twain's speeches.