The extensive study of scheduling problems since the early fifties is motivated by questions arising in production planning, computer system controlling, or even everyday activities such as scheduling an efficient working day in a company or planning an examination period in a university. Scheduling is about all situations in which scarce resources have to be allocated to tasks over time. This project will investigate Liu's conjecture, a simply-defined theoretical scheduling problem about worst-case performance ratio, as an approach to scheduling and sequencing problems.