Immunology as a Metaphor for Computational ... - Napier University

Chapter 3. Immune Systems for Scheduling 51dates and due-dates under which a schedule must be produced.Antigen Universe — a set of antigens representing a sample of the possible scenariosand contingencies that may occur.Antibody — a set of instructions for constructing a schedule.Ag-Ab Complex — combination of an antibody and antigen produces an Ag-Ab complexwhich in this case represents a complete schedule, with start times and finishtimes for each operation. The schedule is produced using the instructions givenby the antibody and the information supplied by the antigen.Match-Score — the match-score represents the strength of the Ag-Ab complex, i.e.in a scheduling scenario the maximum number of time units a job is late inthe schedule produced as a result of matching antibody and antigen. A perfectschedule has a match-score of 0 — the higher the match-score, the worse theschedule.Thus, the scheduling immune system model contains a set of antibodies definingpossible methods for creating schedules, and a set of antigens, representing a sample ofthe potential situations that may arise. The number of antibodies is small compared tothe number of potential situations, therefore each antibody should match (to a greateror lesser extent) a subset of the antigens in the universe. Thus, there are three obviousand important questions to address when designing such an immune system:1. How can one represent both antigens and antibodies ?2. What are the building blocks from which the immune system assembles antibodies,and how are they generated ?3. How are antibodies assembled from these building blocks ?The next section proposes a model — SCHED1 IS, based on immunologicalprinciples, that can accomplish these tasks, and discusses the reasoning behind thedesign choices that were made.