Package management systems tackle resolving package dependencies in different ways, which usually involves associating a package a name and version at least. In this talk I am doing a bit of an exploration of the solution space, including how dependencies are resolved in: - a language specific package manager with a lock file (example: cargo https://doc.rust-lang.org/cargo/) - by a typical distribution (example: Debian https://www.debian.org/ ) - by Nix(https://nixos.org/) and Guix(https://guix.gnu.org/) (example: Guix) Then I will reflect on these solutions from the perspective of reproducible builds(https://reproducible-builds.org/).