Where does scheduling collide?

Johnson's 1954 paper Optimal two- and three-stage production schedules with setup times included gave an algorithm for ordering a set of jobs through machines so that the total time to finish them all is as short as possible, opening the study of scheduling as a formal optimisation problem. Graham, Lawler, Lenstra, and Rinnooy Kan's 1979 survey Optimization and approximation in deterministic sequencing and scheduling organised the field with a notation for describing which resources, jobs, and objectives a problem involves. In this meaning scheduling is the activity of assigning tasks to resources and to positions in time, which job runs where and in what order, so as to optimise a measure such as the time to finish, lateness, or throughput. Here scheduling is a planning and optimisation problem over tasks and machines, not the legal act of placing a drug in a controlled category, and not the cell's timing of when it copies its DNA.[1][2]

Unit

One assignment of tasks to resources and time positions

Recovery means

Not applicable

Measured by

Scored by an objective such as makespan, total flow time, or lateness

The United Nations Single Convention on Narcotic Drugs of 1961 sorted controlled drugs into four numbered schedules, each carrying a different level of legal restriction according to a drug's risk of abuse and its accepted medical use. The United States Controlled Substances Act of 1970 built the same idea into national law, placing substances in Schedules I through V and setting out a procedure by which an agency can add, move, or remove a drug. In this meaning scheduling is the regulatory act of assigning a substance to a legal control category, and rescheduling is moving it between categories. Here scheduling classifies a drug for legal control, and has nothing to do with ordering jobs on machines or with when a cell copies its DNA.[7][3][4]

Unit

One placement of a substance into a numbered legal schedule

Recovery means

Not applicable

Measured by

Determined by statute and by agency review of a drug's abuse potential and accepted medical use

Rasmussen and Painter's 1964 report Evidence for repair of ultra-violet damaged deoxyribonucleic acid in cultured mammalian cells found cells making new DNA outside the single stretch of the cell cycle set aside for copying the genome, the phase biologists treat as the scheduled period of synthesis. The same authors' 1966 paper Radiation-stimulated DNA synthesis in cultured mammalian cells named this repair-driven copying unscheduled DNA synthesis. In this meaning the schedule is the cell's built-in timetable that confines routine replication to one phase, and unscheduled synthesis is the DNA repair that runs off that timetable, now used as a standard test for genetic damage. Here scheduling is a biological timetable for copying DNA, not a plan for running jobs on machines and not a legal category assigned to a drug.[5][6]

Unit

DNA synthesis events occurring outside the scheduled replication phase

Recovery means

Not applicable

Measured by

Detected by autoradiography or by labelled-nucleotide incorporation in cells not in the replication phase