Stability in multi-skill workforce schedules Murat Firat (TU/e) In this work, we are given multi-skill workforce schedules of technicians and jobs. In these schedules, teams are assigned to jobs lasting one workday. A job can be performed by a team of technicians provided that the collective capabilities of the team are above a certain threshold. The problem of constructing these multi-skill workforce schedules under consideration has been defined by France Telecom for the 2007 ROADEF Challenge. The term "skill domain" represents a specialization field and a hierarchical level in certain skill domain hints the degree of expertise. Skill requirements of jobs are specified as the number of technicians needed for each level of specialization. Technicians can use their skills simultaneously in different skill domains while performing a job. We call this assumption simultaneous use of skills. Multi-dimensional skill requirements and simultaneous use of skills are the main aspects making our schedules different from the ones well-studied in the literature. The schedules under the focus of this paper are built using our combinatorial algorithm. Our goal is to characterize the instability by defining a notion of blocking pairs in the classical Marriage model of Gale-Shapley under our multi-skill workforce framework.