The Relaxed Memory Model Zoo

Mapping the space of weak memory models

Comparing two memory models means reading two papers and reconstructing a containment argument nobody wrote down. The Relaxed Memory Model Zoo is a map of 101 models and 145 relations where every edge states how it is known — machine-run litmus test, by construction, or cited — and a consistency gate refuses to ship a map that contradicts itself. This post covers the motivation, the evidence discipline, how the dataset was built (including where AI was used and where it was not trusted), the principles that kept it small, and how to submit corrections. A follow-up post will use the same litmus tests to locate real Rust in the lattice.

Mitigating ABA for Compare-and-Swap: a Survey

Compare-and-swap (CAS) is a central part of many implementations of lock-free algorithms synchronizing values in shared data structures. Without further scaffolding, CAS is inherently prone to the ABA problem. In this post I survey solutions mitigating ABA in the context of CAS towards a high-level classification.