The critical path is defined as the set of packages required to perform the most fundamental actions on a Fedora system. The list of actions is available at Critical_Path_Packages_Proposal#What_is_the_critical_path_of_actions.3F.
Where can I find the critical path?
The list of critical path packages is a dynamically generated list of packages based on package dependencies. The list is generated daily during the Rawhide compose process. For more information on how the list is generated, see Critical_Path_Packages_Proposal#When_and_how_to_determine_packages_within_the_path.
For the most recent list of critical path packages, see http://kojipkgs.fedoraproject.org/mash/rawhide-20180118/logs/critpath.txt