Either joining the same company, starting one together or other method of being in the same organization.
The minimum participation level is "working". Participation levels that don't count:
Funding
Board seat
They both have to be a member of the org and doing work at the same time. Work means at least two days a week in general spending their time advancing the work of the organization as they should, in an organized way, and this must be overlapping time (in terms of dates) for them.
Orgs that count
Company - for profit or not
Vc group
Organization - lobbying group, research, think tanks
University - for example as founders, teachers, researchers
Starting a music school that uses AI
Etc. where they both do things at least partially related to their fame
Orgs that don't count
Totally unrelated things like sports clubs, reading groups on non ai / etc things, church menbership
Intermittent work recording online lessons for Khan academy
Etc
In different companies but both receive investments from same VC
Resolution
Can resolve yes early or no early, but it has to actually start and them be doing work not just a plan for later
Criteria
Public announcements, or other unquestioned statements that it is happening, basically I'll try to determine if it really is happening using all available methods, and then judge based on that