CGP Grey has multiple videos explaining different voting systems as well. https://www.youtube.com/playlist?list=PLqs5ohhass\_RN57KWlJKLOc5xdD9\_ktRg
For future reference, you can move the pacman cache to another drive/partition.
/etc/pacman.conf
CacheDir = /path/to/cache/
CGP Grey has multiple videos explaining different voting systems as well. https://www.youtube.com/playlist?list=PLqs5ohhass\_RN57KWlJKLOc5xdD9\_ktRg