• Articles (14)
Applied Math in Research
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A Surprising Pitfall of Human Judgement and How to Correct It

Algorithms based on machine learning, deep learning, and AI are in the news these days.

By: David Goldberg
Mathematics in Research
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Congruent Numbers Part III

Before demonstrating the claims made in Part I and Part II on this topic, let me mention two simple facts about integer solutions to .

By: David Goldberg
Mathematics in Research
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Congruent Numbers Part II

The method of my first post is too slow to find the side lengths for a triangle of area , which has many digits:

By: David Goldberg
Mathematics in Research
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Congruent Numbers Part I

Usually my posts have a connection to eBay, but this time I’m writing about a recreational math problem that caught my attention.

By: David Goldberg
Applied Math in Engineering
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Peer Groups in Empirical Bayes

In a post from February, I sang the praises of Empirical Bayes, and showed how eBay uses it to judge the popularity of an item.

By: David Goldberg
Applied Math in Engineering
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Statistical Anomaly Detection

Complex systems can fail in many ways and I find it useful to divide failures into two classes.

By: David Goldberg
Applied Math in Engineering
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Fast Approximate Logarithms, Part III: The Formulas

In this post I finally get to the punch line and construct a set of approximations to (actually ) that cover a range of speeds and accuracies.

By: David Goldberg
Applied Math in Engineering
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Fast Approximate Logarithms, Part II: Rounding Error

In Part I, I assumed all computations were done exactly.

By: David Goldberg
Applied Math in Engineering
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Fast Approximate Logarithms, Part I: The Basics

Performance profiling of some of the eBay code base showed the logarithm (log) function to be consuming more CPU than expected.

By: David Goldberg
Applied Math in Engineering
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A Case Study in Empirical Bayes

Empirical Bayes is a statistical technique that is both powerful and easy to use.

By: David Goldberg
Search Science in Engineering
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Diversity in Search

This is a post about how to rank search results, specifically the list of items you get after doing a search on eBay.

By: David Goldberg
Machine Learning in Research
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Personalized Search at eBay, part II

In the first part of this blog posting, I talked about how to estimate a buyer’s propensity to purchase an auction over a fixed price item.

By: David Goldberg
Machine Learning in Research
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Personalized Search at eBay

In this blog post and a succeeding one, I will discuss personalization at eBay.

By: David Goldberg
Structured Data in Engineering
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Items and Products

You often hear that the difference between eBay and other e-Commerce sites is that eBay sells items, other sites sell products.

By: David Goldberg

David Goldberg