Nilpotency, almost nonnegative curvature and the gradient flow

We show that almost nonnegatively curved m-dimensional manifolds are, up to finite cover, nilpotent spaces in the sense of homotopy theory and have C(m)-nilpotent fundamental groups. We also show that up to a finite cover almost nonnegatively curved manifolds are fiber bundles with simply connected fibers over nilmanifolds.Comment: minor corrections in the proof of 2.5.1(II

A Novel Method for the Absolute Pose Problem with Pairwise Constraints

Absolute pose estimation is a fundamental problem in computer vision, and it is a typical parameter estimation problem, meaning that efforts to solve it will always suffer from outlier-contaminated data. Conventionally, for a fixed dimensionality d and the number of measurements N, a robust estimation problem cannot be solved faster than O(N^d). Furthermore, it is almost impossible to remove d from the exponent of the runtime of a globally optimal algorithm. However, absolute pose estimation is a geometric parameter estimation problem, and thus has special constraints. In this paper, we consider pairwise constraints and propose a globally optimal algorithm for solving the absolute pose estimation problem. The proposed algorithm has a linear complexity in the number of correspondences at a given outlier ratio. Concretely, we first decouple the rotation and the translation subproblems by utilizing the pairwise constraints, and then we solve the rotation subproblem using the branch-and-bound algorithm. Lastly, we estimate the translation based on the known rotation by using another branch-and-bound algorithm. The advantages of our method are demonstrated via thorough testing on both synthetic and real-world dataComment: 10 pages, 7figure

A Consistent Regularization Approach for Structured Prediction

We propose and analyze a regularization approach for structured prediction problems. We characterize a large class of loss functions that allows to naturally embed structured outputs in a linear space. We exploit this fact to design learning algorithms using a surrogate loss approach and regularization techniques. We prove universal consistency and finite sample bounds characterizing the generalization properties of the proposed methods. Experimental results are provided to demonstrate the practical usefulness of the proposed approach.Comment: 39 pages, 2 Tables, 1 Figur

Kinematic calibration of Orthoglide-type mechanisms from observation of parallel leg motions

The paper proposes a new calibration method for parallel manipulators that allows efficient identification of the joint offsets using observations of the manipulator leg parallelism with respect to the base surface. The method employs a simple and low-cost measuring system, which evaluates deviation of the leg location during motions that are assumed to preserve the leg parallelism for the nominal values of the manipulator parameters. Using the measured deviations, the developed algorithm estimates the joint offsets that are treated as the most essential parameters to be identified. The validity of the proposed calibration method and efficiency of the developed numerical algorithms are confirmed by experimental results. The sensitivity of the measurement methods and the calibration accuracy are also studied

Prigogine and Pannenberg: Theological and Scientific Perspectives on Contingency and Irreversibility

The author demonstrates how Nobel Laureate Ilya Prigogine\'s pioneering work on dissipative structures and non-equilibrium thermodynamics might be used to answer theological questions about contingency and irreversibility that theologian Wolfhart Pannenberg posed to scientists twenty years ago. Prigogine \'s reformulation of classical dynamics and his mathematical model of irreversibility seem to corroborate Pannenberg \'s claim that natural phenomena must be both contingent and irreversible, if the Christian worldview is correct. The writings of Prigogine and Pannenberg provide an interesting example of the methodological difficulties encountered when comparing scientific and theological worldviews

Prigogine and Pannenberg: Theological and Scientific Perspectives on Contingency and Irreversibility

The author demonstrates how Nobel Laureate Ilya Prigogine\'s pioneering work on dissipative structures and non-equilibrium thermodynamics might be used to answer theological questions about contingency and irreversibility that theologian Wolfhart Pannenberg posed to scientists twenty years ago. Prigogine \'s reformulation of classical dynamics and his mathematical model of irreversibility seem to corroborate Pannenberg \'s claim that natural phenomena must be both contingent and irreversible, if the Christian worldview is correct. The writings of Prigogine and Pannenberg provide an interesting example of the methodological difficulties encountered when comparing scientific and theological worldviews