547,038 research outputs found
A Low-Dimensional Representation for Robust Partial Isometric Correspondences Computation
Intrinsic isometric shape matching has become the standard approach for pose
invariant correspondence estimation among deformable shapes. Most existing
approaches assume global consistency, i.e., the metric structure of the whole
manifold must not change significantly. While global isometric matching is well
understood, only a few heuristic solutions are known for partial matching.
Partial matching is particularly important for robustness to topological noise
(incomplete data and contacts), which is a common problem in real-world 3D
scanner data. In this paper, we introduce a new approach to partial, intrinsic
isometric matching. Our method is based on the observation that isometries are
fully determined by purely local information: a map of a single point and its
tangent space fixes an isometry for both global and the partial maps. From this
idea, we develop a new representation for partial isometric maps based on
equivalence classes of correspondences between pairs of points and their
tangent spaces. From this, we derive a local propagation algorithm that find
such mappings efficiently. In contrast to previous heuristics based on RANSAC
or expectation maximization, our method is based on a simple and sound
theoretical model and fully deterministic. We apply our approach to register
partial point clouds and compare it to the state-of-the-art methods, where we
obtain significant improvements over global methods for real-world data and
stronger guarantees than previous heuristic partial matching algorithms.Comment: 17 pages, 12 figure
Two-Pulse Propagation in a Partially Phase-Coherent Medium
We analyze the effects of partial coherence of ground state preparation on
two-pulse propagation in a three-level medium, in contrast to
previous treastments that have considered the cases of media whose ground
states are characterized by probabilities (level populations) or by probability
amplitudes (coherent pure states). We present analytic solutions of the
Maxwell-Bloch equations, and we extend our analysis with numerical solutions to
the same equations. We interpret these solutions in the bright/dark dressed
state basis, and show that they describe a population transfer between the
bright and dark state. For mixed-state media with partial ground
state phase coherence the dark state can never be fully populated. This has
implications for phase-coherent effects such as pulse matching, coherent
population trapping, and electromagnetically induced transparency (EIT). We
show that for partially phase-coherent three-level media, self induced
transparency (SIT) dominates EIT and our results suggest a corresponding
three-level area theorem.Comment: 29 pages, 12 figures. Submitted to Phys. Rev.
Fast inference in nonlinear dynamical systems using gradient matching
Parameter inference in mechanistic models of
coupled differential equations is a topical problem.
We propose a new method based on kernel
ridge regression and gradient matching, and
an objective function that simultaneously encourages
goodness of fit and penalises inconsistencies
with the differential equations. Fast minimisation
is achieved by exploiting partial convexity
inherent in this function, and setting up an iterative
algorithm in the vein of the EM algorithm.
An evaluation of the proposed method on various
benchmark data suggests that it compares
favourably with state-of-the-art alternatives
Fortuity and Forensic Familial Identification
On July 7, 2010, Los Angeles police announced the arrest of a suspect in the Grim Sleeper murders, so called because of a decade-long hiatus in killings. The break in the case came when California searched its state DNA database for a genetic profile similar, but not identical, to the killer’s. DNA is inherited in specific and predictable ways, so a source-excluding partial match might indicate that a close genetic relative of the matching offender was the Grim Sleeper. California’s apparent success in this case has intensified interest in policymaking for source-excluding partial matching. To date, however, little information about existing state policies, and the wisdom of those policies, has been available. This Article reports the results of a survey of state policies governing source-excluding partial matching — the most complete survey of its kind. The Article also dismantles a distinction drawn by more than a dozen states between partial matches that arise fortuitously during the course of routine database searches and partial matches that are deliberately sought, exposing this distinction as harmful and illogical. In examining this feature of state policies, this Article is immediately relevant to determining how states ought to address the ever-expanding scope of uses to which DNA databases may be put
Efficient Monitoring of Parametric Context Free Patterns
Recent developments in runtime verification and monitoring show that parametric regular and temporal logic specifications can be efficiently monitored against large programs. However, these logics reduce to ordinary finite automata, limiting their expressivity. For example, neither can specify structured properties that refer to the call stack of the program. While context-free grammars (CFGs) are expressive and well-understood, existing techniques of monitoring CFGs generate massive runtime overhead in real-life applications. This paper shows for the first time that monitoring parametric CFGs is practical (on the order of 10% or lower for average cases, several times faster than the state-of-the-art). We present a monitor synthesis algorithm for CFGs based on an LR(1) parsing algorithm, modified with stack cloning to account for good prefix matching. In addition, a logic-independent mechanism is introduced to support partial matching, allowing patterns to be checked against fragments of execution traces
Partial Transfer Learning with Selective Adversarial Networks
Adversarial learning has been successfully embedded into deep networks to
learn transferable features, which reduce distribution discrepancy between the
source and target domains. Existing domain adversarial networks assume fully
shared label space across domains. In the presence of big data, there is strong
motivation of transferring both classification and representation models from
existing big domains to unknown small domains. This paper introduces partial
transfer learning, which relaxes the shared label space assumption to that the
target label space is only a subspace of the source label space. Previous
methods typically match the whole source domain to the target domain, which are
prone to negative transfer for the partial transfer problem. We present
Selective Adversarial Network (SAN), which simultaneously circumvents negative
transfer by selecting out the outlier source classes and promotes positive
transfer by maximally matching the data distributions in the shared label
space. Experiments demonstrate that our models exceed state-of-the-art results
for partial transfer learning tasks on several benchmark datasets
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