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Andrew Roth

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

3 papers
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3

JMLR Journal 2021 Journal Article

Particle-Gibbs Sampling for Bayesian Feature Allocation Models

  • Alexandre Bouchard-Côté
  • Andrew Roth

Bayesian feature allocation models are a popular tool for modelling data with a combinatorial latent structure. Exact inference in these models is generally intractable and so practitioners typically apply Markov Chain Monte Carlo (MCMC) methods for posterior inference. The most widely used MCMC strategies rely on a single variable Gibbs update of the feature allocation matrix. These updates can be inefficient as features are typically strongly correlated. To overcome this problem we have developed a block sampler that can update an entire row of the feature allocation matrix in a single move. In the context of feature allocation models, naive block Gibbs sampling is impractical for models with a large number of features as the computational complexity scales exponentially in the number of features. We develop a Particle Gibbs (PG) sampler that targets the same distribution as the row wise Gibbs updates, but has computational complexity that only grows linearly in the number of features. We compare the performance of our proposed methods to the standard Gibbs sampler using synthetic and real data from a range of feature allocation models. Our results suggest that row wise updates using the PG methodology can significantly improve the performance of samplers for feature allocation models. [abs] [ pdf ][ bib ] [ code ] &copy JMLR 2021. ( edit, beta )

JMLR Journal 2017 Journal Article

Particle Gibbs Split-Merge Sampling for Bayesian Inference in Mixture Models

  • Alexandre Bouchard-Côté
  • Arnaud Doucet
  • Andrew Roth

This paper presents an original Markov chain Monte Carlo method to sample from the posterior distribution of conjugate mixture models. This algorithm relies on a flexible split-merge procedure built using the particle Gibbs sampler introduced in Andrieu et al. (2009, 2010). The resulting so-called Particle Gibbs Split-Merge sampler does not require the computation of a complex acceptance ratio and can be implemented using existing sequential Monte Carlo libraries. We investigate its performance experimentally on synthetic problems as well as on geolocation data. Our results show that for a given computational budget, the Particle Gibbs Split-Merge sampler empirically outperforms existing split merge methods. The code and instructions allowing to reproduce the experiments is available at github.com/aroth85/pgsm. [abs] [ pdf ][ bib ] &copy JMLR 2017. ( edit, beta )

IROS Conference 2004 Conference Paper

Robotic pool: an experiment in automatic potting

  • Fei Long
  • Johan Herland
  • Marie-Christine Tessier
  • Darryl Naulls
  • Andrew Roth
  • Gerhard Roth
  • Michael A. Greenspan

A robotic system is presented which automatically pots (i. e. , sinks) pool balls. A homography is estimated that relates the gantry robot coordinate frame to the overhead (global) camera coordinate frame. This homography is computed by first calculating the mapping between the camera frame and a projection of the robot frame, and then solving the pool table plane equation in the robot frame. A measurement technique has been developed which is based upon a local camera attached to the robot end effector. This local camera allows the robot to be positioned accurately over circular targets placed on the table. The homography and table plane equation are then estimated by establishing correspondences between at least 4 measured target positions in the global camera and robot frames. The resulting homography allows the gantry to be positioned to within an average of 0. 6 mm of a global camera frame position over the extent of a full sized pool table. The system has been used to pot a ball with 67% accuracy over the extent of the table, with a high repeatability.

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