An operation is defined as a planned physical or chemical process that can be executed by one or more functional modules which are sets of hardware units. For example, the operation of solvent evaporation can be carried out using a rotary evaporator or a blow-down evaporator, assuming they are present in the laboratory. The flexibility in choosing which functional module to use for a given operation introduces an operation-to-module assignment problem, which is a part of library synthesis scheduling.