Category Archives: Tech

New GPS Chip With 30cm Accuracy

Broadcom announced a new GPS chip that will give 30-centimeter accuracy instead of today’s 5 meters.

They are able to achieve better accuracy because of the new GPS L5 signal. It is a civilian “safety of life” signal, designed to provide means of secure and robust navigation enough for life-critical applications, like aircraft precision approach guidance. GPS, QZSS (Japanese satellite system) and Galileo (European satellite system) started deploying satellites with L5 support in 2011, and now there are enough satellites in space to start using this functionality.

It should have an impact on self-driving cars. Autonomous vehicles must know precisely where they are, relative to a high-definition map. Using L5 together with together with older L1 and L2 signals gives an order of magnitude improvement in navigation accuracy.

Contextual Bandits and Reinforcement Learning

If you develop personalization of user experience for your website or an app, contextual bandits can help you. Using contextual bandits, you can choose which content to display to the user, rank advertisements, optimize search results, select the best image to show on the page, and much more.

There are many names for this class of algorithms: contextual bandits, multi-world testing, associative bandits, learning with partial feedback, learning with bandit feedback, bandits with side information, multi-class classification with bandit feedback, associative reinforcement learning, one-step reinforcement learning.

Researchers approach the problem from two different angles. You can think about contextual bandits as an extension of multi-armed bandits, or as a simplified version of reinforcement learning.

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Open AI Deep Learning for DotA 2

OpenAI’s bot is the first ever to defeat world’s best players in DotA 2 at The International 2017. It is a major step for AI in eSports. The bot was trained through self-play, but some tactics were hardcoded.

The bot doesn’t play DotA in regular 5v5 setup. It can only beat humans in 1v1 play. Team work will be harder to learn. Also, the bot plays only one character and has a few unfair advantages comparing to human players, e.g. it’s likely to have access to exact information such as distance to other players on the map and health.

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Best Sources of Deep Learning News

The field of deep learning is very active, arguably there are one or two breakthroughs every week. Research papers, industry news, startups, and investments. How to keep up with the news?

There are a few newsletters with well-curated links and summaries:

Papers and code:

  • AI section of is useful if you are looking for the latest research papers.
  • Gitxiv is a collection of source code links for deep Arxiv papers.

Good regular podcasts about deep learning:

Large Text Classification Datasets

Data is the most important component for building a machine learning model. Recently researchers from Google trained a CNN model for image classification on 300 million images and they demonstrated that even on a scale of hundreds of millions of examples adding more data helps to improve the model performance. Apparently, more data is better. But where can you get large datasets if you are doing research on text classification?

I found nice references to a few large text classification datasets in “Text Understanding from Scratch” paper by Xiang Zhang and Yann LeCun. The paper describes a character-level CNN model for text classification. Authors provide benchmarks of different CNN architectures and a few simple models on a few datasets. More recent version of this paper: “Character-level Convolutional Networks for Text Classification” contains more experimental results but it misses some details on dataset usage: which fields to use, how to truncate long texts, etc. If you are looking for information about datasets, read the older paper. If you want to learn more about the character level CNN models, read the latest paper.

Somebody uploaded the datasets to Google Drive, so you can download them here.

If you have other large text classification datasets, please share in comments to this post.

Kaggle Competition: Intel & MobileODT Cervical Cancer Screening

I started looking at Kaggle competitions to practice my machine learning skills. One of currently running competitions is framed as an image classification problem. Intel partnered with MobileODT to start a Kaggle competition to develop an algorithm which identifies a woman’s cervix type based on images.

The training set contains 1481 images split into three types. Kagglers can use 6734 additional images. Some of them come from duplicate patients. Some of the additional images are lower quality. Test sets for two stages of the competition are available, kagglers have to submit a set of predicted probabilities, one for each of 3 classes, for each image of the test set. The total prize pool is $100,000.

I tried to approach the problem in a naïve way: just get a pre-trained Inception V3 image classification model and fine-tune it on this dataset.

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NIPS 2016 Reviews

NIPS (the Conference and Workshop on Neural Information Processing Systems) is a machine learning and computational neuroscience conference held every December. It was first proposed in 1986, and for a long time, it was a small conference. Interest to NIPS significantly increased when deep learning started demonstrating great results in image recognition, speech recognition, and multiple other areas. Last year NIPS had 2500+ papers submitted and 5000+ people in attendance.

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