NP-Incompleteness
2025 in Review
01 Jan 2026
The Perron Method
31 Dec 2025
Oskar Perron was a German mathematician and professor at the University of Heidelberg and then the University of Munich.
Perron had a prolific career in mathematics with 218 publications in several fields. He taught until in 1951 at age 71 but continued teaching until 80 and still doing researching, writing a book in non-Euclidean geometry at age 82 [6].
Perron is also known for providing a relatively simple characterization of a solution to the Dirichlet problem for Laplace’s equations, using subharmonic functions, known as the Perron method, which we explore in this post.
[Book] BPF Performance Tools
28 Dec 2025
In this post I’ll share my notes on the book BPF Performance Tools: Linux System and Application Observability by Brendan Gregg.
This book covers a Linux kernel functionality called BPF, which stands for Berkeley Packet Filter. It was originally developed for network packet analysis (hence the name), but it has been extended as a general mechanism for running user code inside the kernel in a safe virtual machine.
One of its applications is to collect metrics and do event tracing in real-time, being a very powerful tool for performance analysis.
On Complex Systems
20 Dec 2025
Four years ago I decided to change teams within my company. In doing so, I went from doing frontend work on internal tools to doing backend work on a large distributed system. In this new team it was the first time I had to deal with a really complex system.
In this post I’d like to share my thoughts on this topic.
Subharmonic Functions
14 Dec 2025
Frigyes Riesz was a Hungarian mathematician. He was born in Győr in 1880, then part of Austro-Hungarian Empire, and today’s Hungary. He was a professor at Franz Joseph University of Kolozsvár.
After the Treaty of Trianon, in which portions of the kingdom of Hungary went to its neighbors, Kolozsvár became part of Romania and renamed Cluj. The University moved to Szeged, becoming known as Szeged University where Riesz continued to lecture. The one in Cluj was renamed to Dacia Superior University, but today is called Babeș-Bolyai University.
Frigyes is considered one of the founders of functional analysis and has many theorems named after him, such as the Riesz–Fischer theorem and the F. and M. Riesz theorem, which is also named after his brother Marcel Riesz. One of the concepts Riesz came up with is the subharmonic functions, which we study in this post.
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