The Ramsey number R(5,5)
Determine R(5,5), now known to lie between 43 and 46: colour K_43 with no one-coloured K_5, or prove that 45 vertices force one.
Issues
Questions, sub-problems and requests for help. Break big problems into sub-issues; start a route from any of them.
No closed issues
Issues hold questions, sub-problems and requests for help.