Techniques of interest

Note: cross-posted from my website, where I recently attempted to jot down some brief descriptions of the problem domain I’m currently focused on as well as some tools and techniques I am particularly interested in.

Machine learning

One might expect software system behavior and its associated telemetry to be perfectly well-ordered and predictable. Setting aside the Entscheidungsproblem, the complexity, dynamism, and human-driven nature of these systems mean that, in practice, much of the data is actually noisy or chaotic. This provides a promising environment for machine learning and data mining: we have some domain knowledge about the underlying structure and mechanics of the data-generating process, but randomness and noise in the observed signals. Some example families of relevant machine learning approaches and problem formulations here are

• time-series modeling
• clustering and dimensionality reduction
• partial or implicit supervision
• structure extraction/induction
• exploitation of graphical structure
• anomaly or outlier detection
• classifiers and their explanations

Population modeling

Another interesting question is how to pool or combine data across different instances when estimating models. We could consider each entity (eg, host machine running some application) to be totally unique and then estimate models for each in complete isolation. Going the other way, we could naively estimate a single model to cover all instances. The question of how to use metadata or domain knowledge to best interpolate between these extremes is a rich area for exploration, closely related to Bayesian hierarchical modeling or parameter tying in deep neural nets. Ideas from differential privacy may also be relevant in this context.

Software reliability

The challenges of ensuring that software works as intended can easily exceed the nominal effort and cost of creating that software in the first place, especially as you continue to iterate. Beyond the standard best practices around testing code and instrumenting systems, there are exciting opportunities in this area around functional programming, static typing, and the monitoring and testing of complex data-dependent systems like data pipelines and machine learning models.

Approximation algorithms

Resource limitations are an inescapable reality of practical data analytics systems, but surprisingly often it is possible to dramatically expand the operating envelope by accepting some small probability of non-exact results. These techniques are especially appealing where your use case is insensitive to a small approximation error, or if this error is insignificant in comparison to sources of noise or distortion already present in your data.

Product development

How do teams build the right thing, the right way? In general these are hard problems, and can be even trickier on the frontier of novel technologies, applications, or data resources. The effective allocation of scarce effort and attention under conditions of uncertainty within the context of organizational coordination across teams and timezones is a “grand challenge” problem in its own right.

Prior work

Previously, I worked on partially supervised probabilistic modeling of grouped event count data with latent variables. Specifically, I focused on text mining applications where we model word count representations of documents with latent topic models, a class of techniques that can exploit word co-occurrence patterns to recover human-meaningful “topics”. Often these purely statistical topics are not well-aligned to ultimate end-user modeling goals, motivating my research exploring mechanisms by which user-provided side information or domain knowledge could help guide statistical topic recovery, and how these learned topics could then be used in applications such as biomedical research or national security.

Written on January 31st , 2020 by David M. Andrzejewski