How RC2’s π table was made

Khalid Hamadeh shows that the 256-byte PITABLE in Ron Rivest’s RC2 cipher (RFC 2268), and a second unexplained table, are reproduced exactly by a Fisher–Yates shuffle driven by the decimal digits of π, three digits per draw, with code to verify it.

Research · Security · History · Mathematics · Algorithms

Designing more efficient quantum circuits with Claude

Anthropic describes giving Claude plain-language specifications for eight quantum circuits from chemistry, optimization, physics simulation and number theory, plus an automated evaluator. Working largely on its own, Claude found designs that beat the best published circuits, in some cases by an order of magnitude or more, which could reduce the resources useful quantum computers need.

Research · Quantum Computing · AI · Science · Algorithms

Two-Stack Sliding-Window Aggregation

An aggregation is some kind of summary of a set of data. This can be the sum, length, minimum, etc. It is quite common to want to calculate such a summary repeatedly, e.g. “the maximum noise level in dB for the past 30 seconds” for a nuisance detector. In such a case we say there is a sliding window over our data, and we want to aggregate over our window.

Research · Programming · Algorithms · Computer Science · Software Engineering

Mathematicians Build Long-Awaited Graph SandwichThe proof of a decades-old conjecture has given researchers a new way to understand complex networks.

Paulina Rowińska explains how Behague, Iľkovič, and Montgomery completed Kim and Vu's sandwich conjecture, letting hard properties of random regular graphs follow from easier binomial-graph results.

Research · Mathematics · Research · Algorithms